INTESTINAL AND LUMINAL INTESTINAL AND LUMINAL PROTOZOAPROTOZOA     

A parasite is an organism that obtains food A parasite is an organism that obtains food and shelter from another organism and and shelter from another organism and derives all benefits from this associationderives all benefits from this association. . The parasite is termed The parasite is termed obligateobligate when it when it can live only in a host; it is classified as can live only in a host; it is classified as facultativefacultative when it can live both in a host when it can live both in a host as well as in free form. Parasites that live as well as in free form. Parasites that live inside the body are termed inside the body are termed endoparasitesendoparasites whereas those that exist on the body whereas those that exist on the body surface are called surface are called ecto-parasitesecto-parasites. . Parasites that cause harm to the host are Parasites that cause harm to the host are pathogenicpathogenic parasites while those that parasites while those that benefit from the host without causing it any benefit from the host without causing it any harm are known as harm are known as commensalscommensals. .

The organism that harbors the parasite and The organism that harbors the parasite and suffers a loss caused by the parasite is a suffers a loss caused by the parasite is a hosthost. The host in which the parasite lives . The host in which the parasite lives its adult and sexual stage is the its adult and sexual stage is the definitivedefinitive host whereas the host in which a parasite host whereas the host in which a parasite lives as the larval and asexual stage is the lives as the larval and asexual stage is the intermediateintermediate host. Other hosts that host. Other hosts that harbor the parasite and thus ensure harbor the parasite and thus ensure continuity of the parasite's life cycle and continuity of the parasite's life cycle and act as additional sources of human act as additional sources of human infection are known as infection are known as reservoirreservoir hosts. An hosts. An organism (usually an insect) that is organism (usually an insect) that is responsible for transmitting the parasitic responsible for transmitting the parasitic infection is known as the infection is known as the vectorvector..

Taxonomic classification of Taxonomic classification of protozoaprotozoa

Species- Species- examplesexamples

Genus- Genus- examplesexamples

Sub-phylumSub-phylumPhylumPhylumSub kingdomSub kingdom

E. E. histolytichistolyticaa

EntamoebaEntamoebaSarcodinaSarcodina-- - -- - move by move by pseudopodiapseudopodia

Sarcomastig-Sarcomastig-ophoraophorafurther divided intofurther divided into

ProtozoaProtozoa

G. lambliaG. lambliaGiardiaGiardiaMastigophoraMastigophoramove by flagellamove by flagella

P. P. falciparufalciparumm , ,

P. vivaxP. vivax , ,

P. P. malariaemalariae , ,

P. ovaleP. ovale

PlasmodiumPlasmodiumApicomplexaApicomplexano organelle ofno organelle of

locomotionlocomotion

B. coliB. coliBalantidiumBalantidiumCiliophoraCiliophoramove by cilliamove by cillia

E. bienusiE. bienusiEnterocyto-Enterocyto-zoazoa

MicrosporaMicrosporaSpore-formingSpore-forming

V. V. PROTOZOA PROTOZOA Unicellular, chemoheterotrophic, eukaryotic Unicellular, chemoheterotrophic, eukaryotic

organisms of kingdom Protista (3-2000 organisms of kingdom Protista (3-2000 m).m). ProtozoanProtozoan means “first animal”. means “first animal”. 20,000 species, only a few are pathogens.20,000 species, only a few are pathogens. Most are free-living organisms that inhabit water and Most are free-living organisms that inhabit water and

soil. Some live in association with other organisms as soil. Some live in association with other organisms as parasites or symbionts.parasites or symbionts.

Reproduce asexually by fission, budding, or Reproduce asexually by fission, budding, or schizogony.schizogony.

Some exhibit sexual reproduction Some exhibit sexual reproduction ((e.g.: e.g.: ParameciumParamecium)).. TrophozoiteTrophozoite: Vegetative stage which feeds upon : Vegetative stage which feeds upon

bacteria and particulate nutrients.bacteria and particulate nutrients. CystCyst: Some protozoa produce a protective capsule : Some protozoa produce a protective capsule

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

V. V. PROTOZOA (Continued) PROTOZOA (Continued) NutritionNutrition Most are heterotrophic aerobes. Intestinal protozoa Most are heterotrophic aerobes. Intestinal protozoa

can grow anaerobically.can grow anaerobically. Some ingest whole algae, yeast, bacteria, or smaller Some ingest whole algae, yeast, bacteria, or smaller

protozoans. Others live on dead and decaying protozoans. Others live on dead and decaying matter. Parasitic protozoa break down and absorb matter. Parasitic protozoa break down and absorb nutrients from their hosts.nutrients from their hosts.

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

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

Digestion takes place in vacuoles.Digestion takes place in vacuoles. Waste may be eliminated through plasma membrane Waste may be eliminated through plasma membrane

or an anal pore.or an anal pore.

Protozoan classificationProtozoan classification

Four major groups of protozoa are Four major groups of protozoa are recognised and often given the recognised and often given the status of status of phylum*phylum* . Note, however, . Note, however, that in the animal kingdom proper that in the animal kingdom proper (Metazoa* ), phyla are distinguished (Metazoa* ), phyla are distinguished on their different body plans and that on their different body plans and that no comparable body plans are found no comparable body plans are found in Protozoa. in Protozoa.

Protozoan classificationProtozoan classification• The groups areThe groups are: :

• flagellates (or Mastigophora) flagellates (or Mastigophora)

• amoebae (or Sarcodina) amoebae (or Sarcodina)

• sporozoans (or Sporozoa, sporozoans (or Sporozoa, Apicomplexa) and Apicomplexa) and

• ciliates (or Ciliophora). ciliates (or Ciliophora).

• Kingdom AnimaliaKingdom Animalia

• Subkingdom ProtozoaSubkingdom Protozoa

• Phylum SarcomastigophoraPhylum Sarcomastigophora

• Phylum ApicomplexaPhylum Apicomplexa

• Phylum CiliophoraPhylum Ciliophora

• Phylum MicrosporaPhylum Microspora

• Subkingdom MetazoaSubkingdom Metazoa

• Phylum NematodaPhylum Nematoda

• Phylum PlatyhelminthesPhylum Platyhelminthes

Protozoa as Human Parasites

Taxonomy:

Kingdom: Protista

PhylumPhylum::SubphylumSubphylum::GeneraGenera::

SarcomastigophoSarcomastigophorara

Mastigophora Mastigophora ((mastigo mastigo = = whip whip = = flagellatesflagellates))

Trypanosoma, Leishmania, Trypanosoma, Leishmania, Giardia, TrichomonasGiardia, Trichomonas

Sarcodina Sarcodina ((amoebae)amoebae)Entamoeba, Naegleria, Entamoeba, Naegleria, AcanthamoebaAcanthamoeba

ApicomplexaApicomplexaPlasmodium, Toxoplasma, Plasmodium, Toxoplasma, Cryptosporidium, IsosporaCryptosporidium, Isospora

CiliophoraCiliophoraBalantidiumBalantidium

• INTESTINEINTESTINE• Entamoeba Entamoeba

histolyticahistolytica• GiardiaGiardia• IsosporaIsospora• CryptosporidiumCryptosporidium• CyclosporaCyclospora• StrongyloidesStrongyloides• AscarisAscaris• TrichurisTrichuris• hookwormhookworm• pinwormpinworm• tapewormstapeworms• intestinal flukesintestinal flukes

SYSTEMICSYSTEMIC• ToxoplasmaToxoplasma• malariamalaria• filariafilaria• ToxocaraToxocara• hydatid cystshydatid cysts• cysticercosiscysticercosis• SchistosomaSchistosoma• liver flukesliver flukes• lung flukeslung flukes• ProtozoaProtozoa• NematodesNematodes• CestodesCestodes• TrematodesTrematodes

ProtozoaProtozoa

.“eukaryote”..has genetic material .“eukaryote”..has genetic material encased in a nuclear membrane encased in a nuclear membrane (unlike bacteria and viruses)(unlike bacteria and viruses)

• ..classified traditionally by ..classified traditionally by morphology (eg. organelles of morphology (eg. organelles of locomotion), life cycle and locomotion), life cycle and mechanisms of reproduction etc.mechanisms of reproduction etc.

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

• Sarcodina: pseudopodia, e.g. Sarcodina: pseudopodia, e.g. Entamoeba histolyticaEntamoeba histolytica

• Apicomplexa: apical complex, no Apicomplexa: apical complex, no locomotor apparatus;locomotor apparatus;

• sexual reproduction, e.g. sexual reproduction, e.g. cryptosporidium, malaria, cryptosporidium, malaria, toxoplasmatoxoplasma

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

INTESTINAL PROTOZOAINTESTINAL PROTOZOA

• PathogenicPathogenic• Entamoeba histolyticaEntamoeba histolytica• Balantidium coliBalantidium coli• Giardia lambliaGiardia lamblia• Dientamoeba fragilisDientamoeba fragilis• Cryptosporidium parvumCryptosporidium parvum• Enterocytozoon bieneusiEnterocytozoon bieneusi• Septata intestinalisSeptata intestinalis• Cyclospora cayetanensisCyclospora cayetanensis• Isospora belliIsospora belli

• CommensalCommensal• Entamoeba hartmaniEntamoeba hartmani• Entamoeba disparEntamoeba dispar• Entamoeba coliEntamoeba coli• Endolimax nanaEndolimax nana• Iodamoeba bütschliiIodamoeba bütschlii• Chilomastix mesniliChilomastix mesnili• Trichomonas hominisTrichomonas hominis• Blastocystis hominisBlastocystis hominis

•SarcodinaSarcodina:: (**=pathogenic)(**=pathogenic)

Entamoeba Entamoeba histolyticahistolytica**              **             

Entamoeba dispar 

Iodomoeba butschliiIodomoeba butschliiDientamoeba fragilis*Dientamoeba fragilis***Endolimax nana  Endolimax nana  Entamoeba coliEntamoeba coliEntamoeba hartmaniEntamoeba hartmani

Entamoeba histolyticaEntamoeba histolytica(amoebiasis)(amoebiasis)

• PhylumPhylum Sarcomastigophora Sarcomastigophora..

• Subphylum - Subphylum - Sarcodina:Sarcodina: pseudopodia, pseudopodia,

• Life CycleLife Cycle                                                  

BiologyBiology• Two morphological stages occur;Two morphological stages occur;• TrophozoiteTrophozoite - metabolically active - metabolically active

invasive stage, moves with pseudopodia, invasive stage, moves with pseudopodia, ingests RBC, lives in  colon and is found ingests RBC, lives in  colon and is found in fresh diarrheal stool; in fresh diarrheal stool;

• divides by binary fission.divides by binary fission.• Trophozoite 10-60 µmTrophozoite 10-60 µm• cogwheel distribution of nuclear cogwheel distribution of nuclear

chromatinchromatin• HematophagousHematophagous• unidirectional movement with unidirectional movement with

pseudopodiapseudopodia

• CystCyst - "vegetative" inactive form - "vegetative" inactive form resistant to unfavourable resistant to unfavourable environmental conditions outside environmental conditions outside human host;human host;

• 4 nuclei 4 nuclei • This is the infective form resistant to This is the infective form resistant to

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

through stomachthrough stomach• cyst 10-20 µmcyst 10-20 µm• chromotoidal body         chromotoidal body        

AdaptationsAdaptations

• Cyst: a dormant form characterized Cyst: a dormant form characterized by a hardened external covering in by a hardened external covering in which metabolic activity has ceased.which metabolic activity has ceased.– Form in response to nutrient deficiency, Form in response to nutrient deficiency,

drought, and decreased oxygen drought, and decreased oxygen concentration, or pH or temperature concentration, or pH or temperature changes.changes.

– Emerge when conditions improveEmerge when conditions improve

Contractile vacuoleContractile vacuole

• An organelle that expels fluid from An organelle that expels fluid from the cell. the cell.

• Freshwater organisms are usually Freshwater organisms are usually hypertonic relative to their hypertonic relative to their environment so water continually environment so water continually diffuses into them. diffuses into them.

• To maintain homeostasis, it must use To maintain homeostasis, it must use contractile vacuole to rid cell of contractile vacuole to rid cell of excess water.excess water.

PathogenesisPathogenesis

•Digests (liquifies) human host Digests (liquifies) human host cells (colon wall, neutrophils, liver cells (colon wall, neutrophils, liver cells)cells)

•Disease statesDisease states::-- asymptomatic carrier- asymptomatic carrier--- symptomatic infection symptomatic infection-- amoebic dysentery - mucoid amoebic dysentery - mucoid bloody    bloody    -- amoebic - liver or lung abscess amoebic - liver or lung abscess

DiagnosisDiagnosis::

• - - stool examination stool examination - - for trophozoites for trophozoites and cystsand cysts- - amoebic serologyamoebic serology- - abscess aspirateabscess aspirate  - - Entamoeba disparEntamoeba dispar  a non-pathogen   a non-pathogen is indistinguishable by microscopy is indistinguishable by microscopy and is a much more common and is a much more common intestinal protozoan than intestinal protozoan than Entamoeba Entamoeba histolyticahistolytica. Antigen capture and PCR . Antigen capture and PCR tests can distinguish tests can distinguish E. disparE. dispar from from E. E. histolytichistolytica in heavier a in heavier infections.             infections.            

•TreatmentTreatment::Invasive states (Dysentery, Invasive states (Dysentery, Liver abscess): Liver abscess): metronidazolemetronidazole

•Carrier states: diiodoquine, Carrier states: diiodoquine, diloxanide furoate, or diloxanide furoate, or paromomycinparomomycin

Other Other SarcodinaSarcodina

PhagosytosisPhagosytosis