classifiaction & visualization of infective agents - y2s2
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Classification & Visualization
of Infective AgentsRumala Morel
Department of Parasitology
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INFECTION MODULE 1 Y2S2
SYSTEMATIC STUDY
OF
INFECTIVE AGENTS
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Infective Agents
Viruses
Bacteria
FungiProtozoa
Helminths
(Prions) Infective proteinsArthropods
Ectoparasites & vectors of disease
Spongiform
encephalopathy
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Visualizing microorganisms
Different stains
Microscopy- Light Microscopy
bright fieldphase contrast
dark ground
fluorescentElectron Microscopy
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1. CONDENSER lens
focuses light on the
specimen
2. Light then passesthrough OCULAR &
OBJECTIVE lenses
Magnified Image
Bright field Microscope
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Howdoesit
work?
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Dark ground
microscopy
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Phase contrast
microscopy
Dark ground
microscopy
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Visualization of Parasites
Hand lens /magnifying glass
helminth adults, arthopods
Light Microscopy Low power x10 helminth eggs
High power x40 protozoan cysts &trophozoites
Oil immersion x100 protozoa eg. malaria
Technique depends on the degree of
magnification needed.
SIZE OF THE PARASITE
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Biological classification
Carolus Linnaeus 18th century
(Systema naturae - 1735)
Grouped species according to
shared physical characteristics.
Introduced
Binominal classification:
Genus & specieseg. Homo sapiens
http://en.wikipedia.org/wiki/Carolus_Linnaeushttp://en.wikipedia.org/wiki/Carolus_Linnaeus -
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First sorted into large groups and thereafter
subdivided to contain fewer and fewer organismbut sharing more and more common features
Biological classification - by Linnaeus - 18th century
Kingdom
Phylum
Family
Class
Order
Genus
species
Genus species
Binomial system
Plasmodium falciparum
Naming organism
Scientific names
italicize OR underline
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PROKARYOTE
Eg. bacteria
EUKARYOTE
Eg. protozoa
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Virus = an infectious agent,
consisting of genetic materialDNA or RNA wrapped up in a
protein coat.
100 x smaller than bacteria
Invades living cells and uses
them to keep itself alive and to
replicate itself.
Some viruses can cause life-
long and chronic infections
eg. Herpes viruses
Viruses
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Viral classification
DNA or RNA
Size and Morphology
Susceptibility to physical & chemical agents
Symptoms
Pathology
Host and tissue tropism
Transmission
Immunological properties
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VIRUSES
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DNA RNA
Parvoviridae Papovaviridae
Adenoviridae
Herpesviridae Poxviridae
Hepadnaviridae
Picornaviridae
Reoviridae Togaviridae
Arenaviridae Coronaviridae Retroviridae Bunyaviridae Orthomyxoviridae Paramyxoviridae Rhabdoviridae
VIRUSES
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SHAPEBacteria
Classification
is based on SHAPE
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Bacteria
Gram POSITIVE Cocci Gram NEGATIVE Bacilli
Gram POSITIVE Bacilli Gram NEGATIVE Cocci
in clusters in chains
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Fungi
Yeasts & Moulds
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Yeast
Cryptococcus
Yeast-like
Candida
Moulds
Dermatophytes
Dimorphic fungi
Histoplasma
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Parasites
Sporozoa Amoebae
FlagellatesMicrosporidia
Roundworms Flatworms
Cestodes Trematodes
Nematodes
Ciliates
HelminthsProtozoa
Arthropods
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Unicellular
Animal like cells - heterotrophic nutrition -require preformed organic substances
Classified according to method oflocomotion
Trophozoites - actively feed and multiply
Cysts - resistant walls
Most free-living
Protozoa
Binary division
P ti t ( t )
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Protista (protozoans unicellular, eukaryotic)
(1)AMOEBAE
Trophozoites & Cyst(growing stage)
pseudopodia
(false feet)(3) CILIATES
Balantidium coli- cilia(2) FLAGELLATESGiardia lamblia
flagella
(4) A i l
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(4).Apicomplexa
= SPOROZOA
No organelle for
motility
(5). MICROSPORIDIA
spore-forming
Plasmodium Coccidia
PARASITIC PROTOZOA
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PARASITIC PROTOZOA
1.Sporozoa
2.Amoebae
3.Flagellates
5. Microsporidia
Toxoplasma gondii toxoplasmosis
Cryptospordium spp. - diarrhoea
Entamoeba histolytica amoebiasis
Giardia intestinalis diarrhoea
Trichomonas vaginalis trichomoniasis
Leishmania spp. leishmaniasisTrypanosoma spp. - trypanosomiasis
4. Ciliates Balantidium coli- balantidiasis
Plasmodiumspp.- malaria
Babesia - babesiosis
b).Coccidia
a).others
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200 million cases of malaria annually
Killed more humans than any other disease.
1 million deaths /year. 90% in sub-Saharan Africa, an
African child dies of malaria every 30 sec.
Over half the world's
population live in
malarious areas
Malaria
Finger prick screening for
MP = Malarial Parasite
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Main causative organism - Entamoeba histolytica Other causes Balantidium coli, Trichiuris trichiura
Invade colonic mucosa ulcers
Parasitic diarrhoea Blood & mucous
Blood & mucous
diarrhoea
=Amoebic dysenteryPortal vein (blood)
LiverAmoebic hepatitis
Amoebic liver abscess
Entamoeba trohpozoiteEntamoeba cyst
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Parasitic watery diarrhoea
Giardia duodenalis
causes giardiasis
Cryptosporidium
spp. causes
cryptosporidiosisPersistent diarrhea in
AIDS,
other immunosuppressed
CystTrophozoite
ToxoplasmaC it l
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Toxoplasma
encephalitis in
AIDS
Congenital
Toxoplasmosis
Microcephaly
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3 types Visceral Mediterranean, India Mucocutaneous (Espundia)
South America Cutaneous skin ulcers
Leishmaniasis
Leishmania donovani
In Sri LankaVisceral,Cutaneous
& Mucocutaneous
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Helminths
ROUNDWORMS=
NEMATODES
FLATWORMS
TREMATODESCESTODES
NEMATODES INTESTINAL
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NEMATODES
Cylindrical Sexes separate- male smaller
Muscular outer wall - organs are suspended in a
false body cavity (pseudo coelom)
4 moults in Life Cycle
INTESTINALTISSUE
cuticle
muscle layer
body
cavity
Commonest helminthiases (worm infections) in SL
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Enterobius vermicularis
(kiri panuwa)
Transmitted from
person to person
GEOHELMINTHS(soil transmitted worms)
Ascaris lumbricoides
Trichuris triciura
Strongyloides stercoralis
HookwormsNecator americanus (In SL)
Ancylostoma duodenale
Commonest helminthiases (worm infections) in SL
Nematodes
Whipworm = Trichuris trichiura
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Whipworm Trichuris trichiuraSoil transmission similar toAscaris
+ direct feco -oral
Trichiuris eggs Trichiuris adults Ascaris adults
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Hookworms
Pallor/Anaemia
due to blood loss
Adult 1 cm
Sucking blood in
intestine
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Larva currens Cutaneous LarvaMigrans = CLM
Disseminated disease in immunosuppressed
NO EGGS in stool
Only rhabditiform larva in stools
Strongyloidiasis
Strongyloides stercoralis
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Phylum- PLATYHELMINTHES
Flatworms
Class- Cestodes/Tapeworms
Class- Trematodes/Flukes
Features common to Cestodes 1
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Features common to Cestodes 1
Morphology: Flat, ribbon like.
Location: Adults in intestinal tract of
vertebrates.
Size
Echinococcus granulosus
Taenia
few milimeters 10 metres
Features common to Cestodes 2
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Head: Scolex/ Hold-fast organ - attach to hosts
intestine Scolex: sucking grooves, hooks or suckers
Hermaphrodite: segments have both testes &
ovaries (male & female together)
No alimentary tract: absorption through body wall.
Features common to Cestodes 2
Trematodes flat & leaflike
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Trematodes- flat & leaflike,
sexes not separate
(except in blood flukes)
Water borne
[Schistosomes = blood flukes]
Food borne
[tissue flukes]
Cl T t d
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Class- Trematodes
Blood Flukes Tissue Flukes
Tissue flukes
hermaphroditic
Schistosomes
2 sexes are
separate
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ARTHROPODS 1
1. Mosquitos- transmit most important vector borne
diseases in Sri Lanka
2. Lice - Head louse & body louse
- Pubic lousetransmit Louse-borne relapsing fever, Epidemic typhus,
Trench fever
3. Fleas - transmit plague, murine typhus
4. Flies - sand fly transmit leishmaniasis
CLASS INSECTA
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Mosquito borne diseases
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Mosquito borne diseases Arboviruses
Yellow fever
Dengue
Japanese
encephalitis [JE]
Chikungunya
Protozoa Malaria
Helminth - Filariasis
Anopheles
Malaria
Aedes - Dengue
Culex filariasis
- JE
Control findmosquito larva
& eliminate
breeding places
ARTHROPODS 2
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ARTHROPODS 2
Mites - Scabies mite = Sarcoptes scabieii
-Trombiculid mite larvae transmitscrub typhus
CLASS ARACHNIDATicks - transmit tick-borne viral encephalitis,
rickettsiae
&
Ticks spread
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Fleas are vectors ofPLAGUE
Scabies spread
by
scabies mite
p
rickettsial &
viral
disease