404414_intestinal and luminal protozoa

8/12/2019 404414_intestinal and Luminal Protozoa

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INTESTINAL AND LUMINAL

PROTOZOA


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A parasite is an organism that obtains food andshelter from another organism and derives all

benefits from this association. The parasite istermed obligatewhen it can live only in a host;it is classified as facultativewhen it can liveboth in a host as well as in free form. Parasites

that live inside the body are termedendoparasiteswhereas those that exist on thebody surface are called ecto-parasites.Parasites that cause harm to the host are

pathogenicparasites while those that benefitfrom the host without causing it any harm areknown as commensals.


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The organism that harbors the parasite and suffersa loss caused by the parasite is a host. The host

in which the parasite lives its adult and sexualstage is the definitivehost whereas the host inwhich a parasite lives as the larval and asexualstage is the intermediatehost. Other hosts

that harbor the parasite and thus ensurecontinuity of the parasite's life cycle and act asadditional sources of human infection are knownas reservoirhosts. An organism (usually an

insect) that is responsible for transmitting theparasitic infection is known as the vector.


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Taxonomic classification of

protozoa Sub kingdomPhylumSub-phylumGenus-examples

Species-examples

ProtozoaSarcomastig-ophorafurther divided into

Sarcodina-- -move by pseudopodia

EntamoebaE.histolytica

Mastigophoramove by flagella

Giardia

G. lamblia

Apicomplexano organelle of

locomotion

PlasmodiumP.falciparum,

P. vivax,

P.malariae,

P. ovale

Ciliophoramove by cillia

Balantidium

B. coli

MicrosporaEnterocyto-zoaE. bienusi


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V. PROTOZOA

Unicellular, chemoheterotrophic, eukaryotic organisms of

kingdom Protista (3-2000 m).

Protozoanmeans first animal.

20,000 species, only a few are pathogens.

Most are free-living organisms that inhabit water and soil.

Some live in association with other organisms as parasites

or symbionts.

Reproduce asexually by fission, budding, or schizogony.

Some exhibit sexual reproduction (e.g.: Paramecium).

Trophozoite: Vegetative stage which feeds upon bacteria

and particulate nutrients.Cyst: Some protozoa produce a protective capsule under

adverse conditions (toxins, scarce water, food, or oxygen).


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V. PROTOZOA (Continued)

Nutrition

Most are heterotrophic aerobes. Intestinal protozoa cangrow anaerobically.

Some ingest whole algae, yeast, bacteria, or smallerprotozoans. Others live on dead and decaying matter.Parasitic protozoa break down and absorb nutrients fromtheir hosts.

Some transport food across the membrane.Others have a protective covering (pellicle) and required

specialized structures to take in food. Ciliates take in food through a cytostome.

Digestion takes place in vacuoles.

Waste may be eliminated through plasma membrane or ananal pore.


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Protozoan classification

Four major groups of protozoa arerecognised and often given the status of

phylum*. Note, however, that in theanimal kingdom proper (Metazoa*), phylaare distinguished on their different body

plans and that no comparable body plansare found in Protozoa.
http://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/glossary/glossary.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/glossary/glossary.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/glossary/glossary.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/glossary/glossary.htm


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Protozoan classification

The groups are: flagellates(or Mastigophora) amoebae(or Sarcodina)

sporozoans(or Sporozoa, Apicomplexa)and

ciliates(or Ciliophora).
http://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot4.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot5.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot6.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot7.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot7.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot6.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot5.htmhttp://www-biol.paisley.ac.uk/Courses/Tatner/biomedia/units/prot4.htm


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Kingdom Animalia Subkingdom Protozoa Phylum Sarcomastigophora

Phylum Apicomplexa

Phylum Ciliophora Phylum Microspora

Subkingdom Metazoa

Phylum Nematoda Phylum Platyhelminthes


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Protozoa as Human ParasitesTaxonomy:Kingdom: Protista

Genera:Subphylum:Phylum:

Trypanosoma, Leishmania, Giardia,

Trichomonas

Mastigophora (mastigo

= whip = flagellates)

Sarcomastigophora

Entamoeba, Naegleria,Acanthamoeba

Sarcodina (amoebae)

Plasmodium, Toxoplasma,Cryptosporidium, Isospora

Apicomplexa

BalantidiumCiliophora


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INTESTINE Entamoeba histolytica

Giardia

Isospora Cryptosporidium Cyclospora Strongyloides

Ascaris Trichuris hookworm pinworm

tapeworms intestinal flukes

SYSTEMIC Toxoplasma

malaria

filaria Toxocara hydatid cysts cysticercosis

Schistosoma liver flukes lung flukes Protozoa

Nematodes Cestodes Trematodes


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Protozoa

.eukaryote..has genetic material encasedin a nuclear membrane (unlike bacteria

and viruses) ..classified traditionally by morphology

(eg. organelles of locomotion), life cycle

and mechanisms of reproduction etc.


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Mastigophora: movement with flagella -e.g. Trichomonas, Giardia

Sarcodina: pseudopodia, e.g. Entamoebahistolytica

Apicomplexa: apical complex, no

locomotor apparatus; sexual reproduction, e.g. cryptosporidium,

malaria, toxoplasma

Ciliophora: movement with cilia, e.g.Balantidium.


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INTESTINAL PROTOZOA

Pathogenic Entamoeba histolytica Balantidium coli

Giardia lamblia Dientamoeba fragilis Cryptosporidium parvum Enterocytozoon bieneusi

Septata intestinalis Cyclospora cayetanensis Isospora belli

Commensal Entamoeba hartmani Entamoeba dispar

Entamoeba coli Endolimax nana Iodamoeba btschlii Chilomastix mesnili

Trichomonas hominis Blastocystis hominis


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Entamoeba histolytica(amoebiasis)

Phylum Sarcomastigophora.

Subphylum - Sarcodina:pseudopodia,

Life Cycle


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Biology

Two morphological stages occur; Trophozoite- metabolically activeinvasive stage, moves with pseudopodia,ingests RBC, lives in colon and is found in

fresh diarrheal stool; divides by binary fission. Trophozoite 10-60 m cogwheel distribution of nuclear chromatin Hematophagous unidirectional movement with

pseudopodia


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Cyst- "vegetative" inactive form resistantto unfavourable environmental conditions

outside human host; 4 nuclei This is the infective form resistant to

stomach acid if swallowed survives up to 30 days; excyst to trophozoite on passing through

stomach cyst 10-20 m chromotoidal body


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Adaptations

Cyst: a dormant form characterized by ahardened external covering in which

metabolic activity has ceased. Form in response to nutrient deficiency,

drought, and decreased oxygenconcentration, or pH or temperature changes.

Emerge when conditions improve


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Pathogenesis

Digests (liquifies) human host cells(colon wall, neutrophils, liver cells) Disease states:

-asymptomatic carrier--symptomatic infection-amoebic dysentery - mucoid

bloody-amoebic - liver or lung abscess

i i


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Diagnosis:

- stool examination - for trophozoites and

cysts- amoebic serology- abscess aspirate- Entamoeba dispar a non-pathogen is

indistinguishable by microscopy and is amuch more common intestinal protozoanthan Entamoeba histolytica. Antigen

capture and PCR tests can distinguish E.disparfrom E. histolytica in heavierinfections.


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Treatment:

Invasive states (Dysentery,Liver abscess): metronidazole

Carrier states: diiodoquine,diloxanide furoate, orparomomycin


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SarcodinaOther


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404414_intestinal and luminal protozoa

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