Infectious Disease Process.pptx

8/20/2019 Infectious Disease Process.pptx

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Infectious Disease

Process


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Topics

Definition of Terms

Sporadic

Endemic

Hyperendemic

Epidemic

Pandemic

Infection

Infestation

Disease

Disorder

Sign

Symptom

Syndrome

Pathogenicity

Virulence


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Chain of Infection

Etiologic Agent

Classification of Etiologic Agents

Examples of Diseases and their Etiologic Agents

Reseroir

Incu!atory Carriers

Inapparent Infections

Conalescent Carriers

Chronic Carriers

Portal of Exit

"ode of Transmission

Direct Transmission

Indirect Transmission

Contact Precautions

Droplet Precautions

Air!orne Precautions

Portal of Entry

Enteral Route

Parenteral Route

Suscepti!le Host

Stages of Infectious Disease

Incu!ation Stage

Prodromal Stage

Acute Stage

Declining Stage Conalescent Stage


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#!$ecties

Descri!e ho% infections are spread

&amiliari'e the terms used in categori'ing spread of infections

Explain the infectious disease process and the chain of infectio

(no% the different classification of etiologic agents and some

of the diseases they may cause


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Patterns of Disease #ccurrence

Sporadic

Disease occurs infre)uently and irregularly

Endemic

Constant presence or usual prealence of a disease or infectious agent i

population within a geographic area

Hyperendemic

Persistent* high leels of disease occurrenceEpidemic

A sudden increase in the num!er of cases of a disease a!oe %hat is nor

expected in that population in that area

Pandemic

An epidemic that has spread oer seeral countries or continents and ha

affected a large num!er of people


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,hat is the difference !et%een

infection and infestation-

Infection

Inasion of a !ody !y an etiologic agent

Infestation

Presence of etiologic agents in the s.in* hair* or nails* of a h


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,hat is the difference !et%een

disease and disorder-

Disease

Appearance of signs or symptoms !rought a!out

!y the presence of an etiologic agent or !y

a!normal function

Disorder

Appearance of signs or symptoms !rought a!out

!y a!normal function


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Sign

#!$ectie finding perceied !y an examiner

/lood in stool* rashes Symptom

Su!$ectie indication of disease perceied !y

the patient

Stomachache* headache* fatigue

Syndrome

0roup of signs and symptoms


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Chain of Infection

Elements lin.ed together %hich affect

transmission of infection


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I1 Etiologic agents

A1 "eta'oan

/1 Proto'oan

C1 &ungi

D1 /acteria

E1 Ric.ettsia

&1 Viruses

01 Prions


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A1 "eta'oans

"ulticellular animals* mostly parasitic

(ingdom Animalia

Examples of diseases2

31 Trichinellosis

41 Schistosomiasis

51 Hoo.%orm infection

61 &ilariasis


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"eta'oanparasites

Helminths

Annelids

7eeches

8ematodes &lat%orms

Cestodes Trematode

Arthropods


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31 Trichinellosis

Also called trichinosis

Caused !y Trichinella

spiralis* an intestinal

round%orm

transmitted througheating undercoo.ed

meat* usually por.


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41 Schistosomiasis

Schistosoma japonicum, Schistosoma haematobium, Schisto

mansoni

A !lood flu.e transmitted through contaminated %ater

Symptoms are related to num!er and location of eggs in the


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51 Hoo.%orm infection

Ancylostoma duodenale

Necator americanus

Transmitted through feces9

contaminated %ater and soil Can cause chronic anemia that

often results in retarded mental

and physical deelopment of

children


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61 &ilariasis

Wuchereria bancrofti

Brugia malayi

Chronic infection may

cause elephantiasis


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:nholy Three of Parasitic Infection

Round%orm

Ascaris lumbricoides

Hoo.%orm

Ancylostoma duodenale

Necator americanus

,hip%orm

Trichuris trichiura


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/1 Proto'oans

Single9celled organisms %ith %ell9defined nucleus

(ingdom Protista

31 Amoe!iasis

41 0iardiasis51 "alaria

61 Toxoplasmosis

5. Pneumocystis carinii pneumonia


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31 Amoe!iasis

Diarrheal illness

ntamoeba histolytica ntamoeba coli !not pathologic"


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41 "alaria

A mos)uito9!orne

disease and one of the

top three infectious

diseases in the %orld

Plasmodium falciparum

Plasmodium #i#a$

Plasmodium malariae

Plasmodium o#ale


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Considered as the top three infectious

diseases in the %orld2

"alaria

Tu!erculosis

HIV


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51 0iardiasis

Infection of the upper

small intestine %hich

causes diarrheal

illness

%iardia lamblia


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51 Toxoplasmosis

To$oplasma gondii

Transmitted to humans !y

cats and undercoo.ed meat

"ay cause fetal death if it

infects a pregnant %oman


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61 Pneumocystis carinii

pneumonia ;PCP<

#ften fatal :sually seen in patients %ith

compromised immune system

Infected %ith HIV


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C1 &ungi

8on9motile* filamentous organisms

Cause diseases %hich are hard to treat

(ingdom &ungi

(ingdom Protista9 slime molds

31 Histoplasmosis

41 Candidiasis


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31 Histoplasmosis

&istoplasmacapsulatum

Transmitted !y

inhaling dust

from soil that

contains birddroppings

Seerity aries

%idely* !ut

commonly

affects the lungs


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41 Candidiasis

'andida albicans

Transmitted !y contact

%ith infected patients and

carriers

Causes lesions on the s.in

or mucus mem!ranes*

including thrush anduloaginitis

Symptoms can !e seere in

immunocompromised

patients


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D1 /acteria

Single9celled organisms %ithout nucleus

(ingdom "onera

Tu!erculosis

Chlamydia

0onorrhea

#ther accine9preenta!le diseases


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31 Tu!erculosis

A chronic lungdisease

A ma$or cause

of disa!ility in

many parts of

the %orld (ycobacterium

tuberculosis


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41 Chlamydia and

0onorrhea

'hlamydiatrachomatis

Neisseria

gonorrhea

Considered as

the most

%idespread

sexually

transmitted

disease


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E1 Ric.ettsia

:sually found in the cells of lice* tic.s* fleas* and mites

Smaller than most !acteria and share some characteristics

of iruses

0enus of !acteria

31 Roc.y "ountain Spotted &eer

41 Typhus


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31 Roc.y "ountain

Spotted &eer

Tic.9!ornesystemic

disease

)ic*ettsia

ric*ettsii


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41 Types of typhus

and carriers2

a1 Epidemic typhus

7ouse9!orne typhus

Caused !y )ic*ettsia pro+ae*ii

!1 "urine typhus

Carried !y the rat or cat flea

Caused !y )ic*ettsia typhi

c1 Scru! typhus

Carried !y mites

Caused !y -rientia tsutsugamushi


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&1 Viruses

Small organisms consisting of an outer protein coat and anR8A or D8A core

Can only gro% inside liing cells

Influen'a

SARS

AIDS

Hepatitis


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01 Prions

Infectious agents%ithout genes

Seem to !e comprised

of protein %hich

replicates in animal or

human tissues Cause seere damage

to the !rain


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Prion diseases in humans2

C=D ;Creut'feld9=aco! Disease<

0SS ;0erstmann9Straussler9Schein.er Syndrome<

&&I ;&amilial &atal Insomnia<

(uru


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A!ility of an etiologic agent to cause

harm is measured !y t%o factors

Pathogenicity A!ility of an etiologic agent to cause disease in a

suscepti!le host

Virulence

Degree of harm caused !y an etiologic agent in a

suscepti!le host


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II1 Reseroirs

:sual ha!itat %here etiologic agent lies and multiplies

31 Humans

41 Animals

51 Enironment

R i


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31 Human Reseroirs

Acute clinical cases Carriers

,h i h diff !


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,hat is the difference !et%een acute

clinical cases and carriers-

Acute Clinical Cases People %ho are infected %ith the disease agent and

!ecome ill

Their contacts and actiities may !e limited

Carriers

People %ho har!or infectious agents !ut are not ill

Actiities are not restricted !y illness

,hi h t i . f di


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,hich present more ris. for disease

transmission-

Acute clinical cases are more li.ely to !e diagnosed andtreated than carriers

Carriers present more ris. for disease transmission than

acute clinical cases !ecause their contacts are una%are of

their infection

T f i


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Types of carriers

A1 Incu!atory carriers

/1 Inapparent infections

C1 Su!clinical cases

D1 Conalescent carriers

E1 Chronic carriers

A I ! t C i


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A1 Incu!atory Carriers

People infected %ith an etiologic agent has not yetdeeloped the disease* !ut !egin transmitting the

etiologic agent to others

A person infected %ith measles !egins to shed the irus in

nasal and throat secretions a day or t%o !efore any coldsymptoms or rash are noticea!le

HIV infection may !e present for years !efore the person

deelops any sign or symptom

/ Inapparent Infections


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/1 Inapparent Infections

People infected %ith an etiologic agent %ill not deelopthe disease* !ut !egin transmitting the etiologic agent to

others

#f eery 3>> indiiduals infected %ith the poliomyelitis

irus* only one !ecomes paraly'ed1 &our others %ill hae amild illness %ith feer* malaise* headache* nausea and

omiting* !ut ?@ out of the 3>> %ill hae no symptoms at

all* although they pass the irus in their feces

C Su!clinical Cases


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C1 Su!clinical Cases

A type of inapparent infection %herein a huge num!er ofpeople gets infected !efore anyone deelops the disease

In meningococcal meningitis* the num!er of su!clinical

cases may !e )uite high !efore a single clinical case

appears

D Conalescent Carriers


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D1 Conalescent Carriers

People infected %ith an etiologic agent %ho deeloped thedisease and has recoered continue to transmit the

etiologic agent for %ee.s or months

Salmonella patients may excrete the !acteria in feces for

seeral %ee.s* and rarely een for a year or more This is most common in infants and young children

Treatment %ith inappropriate anti!iotics may prolong the

conalescent carrier phase

E Chronic carriers


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E1 Chronic carriers

People infected %ith an etiologic agent %ho deeloped the d

and has recoered continue to transmit the etiologic agent for longer

The chronic carrier state is common follo%ing hepatitis / in

%hether or not the person !ecomes ill* and may !e lifelong

Ris. of deeloping chronic hepatitis / depends on the personinfection

A!out ?>B of infants infected at !irth !ecome chronic carrie

irus* compared %ith only 393>B infected after age @

Important to gie hepatitis / accine to ne%!orns

4 Animal Reseroirs


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41 Animal Reseroirs

Can !e descri!ed in the same %ay as human reseroirs2

Acute clinical cases

Carriers

5 Enironmental Reseroirs


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51 Enironmental Reseroirs

Plants* soil* and %ater

"ost fungal agents lie and multiply in the soil

#rganism that causes histoplasmosis lies in soil %ith high

organic content and undistur!ed !ird droppings

Agents that cause tetanus* anthrax* and !otulism are

%idely distri!uted in soil

Agent of 7egionnaires Disease lies in %ater* including hot

%ater heaters

III Portal of Exit


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III1 Portal of Exit

Route !y %hich etiologic agents escape from the reseroir Secretions* excretions

IV "ode of Transmission


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IV1 "ode of Transmission

Path of transfer of etiologic agentfrom a reseroir to a suscepti!le

host

Vertical transmission

Hori'ontal transmission

Direct transmission

Indirect transmission

Direct Transmission


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Direct Transmission

Due to direct contact %ith the reseroir

Direct Transmission


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Direct Transmission

Re)uires physical contact !et%een an infected person and asuscepti!le person* and the physical transfer of microorganisms

Touching an infected indiidual* .issing* sexual contact* contact %ith

oral secretions* or contact %ith !ody lesions

Re)uires close contact %ith an infected indiidual

:sually occurs !et%een mem!ers of the same household or close

friends and family Diseases that spread exclusiely !y direct contact are una!le to

surie for significant periods of time a%ay from a host

Sexually transmitted diseases are almost al%ays spread through direct

contact* as their etiologic agents are extremely sensitie to drying



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31 Inanimate mechanisms Inoles transmission through nonliing ehicles

41 Animate mechanisms

Inoles transmission through liing ectors

31 Inanimate "echanisms


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31 Inanimate "echanisms

A1 &omites/1 Droplet nuclei

A1 &omites


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A1 &omites

Contaminated touch surfaces

Transmit etiologic agents to

suscepti!le host especially if

etiologic agents are capa!le of

suriing on surfaces for anextended period of time


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/1 Droplet 8uclei


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p

Residue from eaporated droplets

Aerosol transmission9 inhalation of

infectious particles

Particles up to 3>> m in si'e are

considered inhala!le ;inspira!le<

Air!orne transmission

Droplet transmission

,hat is the difference !et%een air!orne


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transmission and droplet transmission-

/oth inole transmission of droplet nuclei

The difference lies in the si'e of droplet nuclei !eing

transmitted

Air!orne Transmission


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Small droplets ; 3> m<

Trael a long distance

Droplet nuclei or dust particles containing microorganisms re

suspended in air for long periods of time

#rganisms are capa!le of suriing for long periods of time o

!ody and resistant to drying

#rganisms enter the upper and lo%er respiratory tracts

A limited num!er of diseases are capa!le of air!orne transmi


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Droplet Transmission


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7arge droplets ;3> m<

Short distance

Coughing* snee'ing* or tal.ing* certain medical procedures

;!ronchoscopy<

Too large to !e air!orne for long periods of time

Fuic.ly settle out of air

Reduced %ith the use of personal protectie !arriers


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41 Animate "echanisms

/iological ectors s1 "echanical Vectors


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/iological ectors s1 "echanical Vectors

Can !iological ectors also !ecome

hosts-


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Vector

Is a liing organism that transmits an infectious agent

from an infected animal to a human or another animal

/iological ector

"os)uitos* tic.s

"ay carry pathogens that can multiply %ithin their !odies and!e deliered to ne% hosts usually !y !iting

"echanical ector &lies

Can pic. up infectious agents on the outside of their !odies

and transmit them through physical contact


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VI1 Suscepti!le Host


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Suscepti!ility 7i.elihood of !eing infected !y an etiologic agent

Affected !y2

0enetic factors

0eneral resistance

Immunity

The Stages of Infectious Disease


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31 Incu!ation stage41 Prodromal stage

51 Acute stage

61 Declining stage

@1 Conalescent stage

31 Incu!ation Stage


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Silent stage 7ength of the incu!ation stage depends on the etiologic

agent

Some hae ery short incu!ation stage %hile others

re)uire a longer time

Incu!ation stage ends %hen the first signs and symptomsof the infectious disease appear

41 Prodromal Stage


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&irst signs andGor symptoms occur

7asts a!out one or t%o days

Signs and symptoms sho% that a disease process is ta.ing

place

51 Acute Stage


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Disease reaches its highest point of deelopment

Signs and symptoms may !ecome more seere

Signs and symptoms during this stage can help determine

one disease from another

61 Declining Stage


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Signs and symptoms start to su!side

Etiologic agent is still present

Health of the host starts to return to normal

@1 Conalescent Stage


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Signs and symptoms hae nearly anished

Etiologic agent has !een mostly eliminated

Host !egins to regain strength and returns to original state

of health


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The Infectious Disease Spectrum


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Impact of disease agents on human host populations is comp

If a large num!er of indiiduals are e)ually exposed to an inagent* they do not all respond in the same manner

/road range of host responses2

Some do not !ecome infected at all

Some !ecome infected !ut deelop no signs nor symptoms

Some !ecome infected and deelop mild or moderate signs

Some !ecome infected and deelop seere signs or symptom

Some die as a result of their infection


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"any diseases share the same signs and symptoms

Treatment and control measures are ery different for

these diseases

7a!oratory identification of specific disease agent isimportant in any epidemiological inestigation

This ariation is due to2


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Capacity of the agent to produce disease

Differing leels of resistance of the hosts

In summary2


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In order for infection and disease to occur in an indiidual*

a process inoling six related components must occur

Chain of Infection

To stop the spread of disease* one or more of these lin.s

must !e !ro.en

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