1. INTESTINAL AND LUMINAL PROTOZOA

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

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

4. Taxonomic classification of protozoa
Sub kingdom
Phylum
Sub-phylum
Genus- examples
Species- examples
Protozoa
Sarcomastig-ophora
further divided into
Sarcodina-- - move by pseudopodia
Entamoeba
E. histolytica
Mastigophora
move by flagella
Giardia
G. lamblia
Apicomplexa
no organelle of
locomotion
Plasmodium
P. falciparum,
P. vivax,
P. malariae,
P. ovale
Ciliophora
move by cillia
Balantidium
B. coli
Microspora
Spore-forming
Enterocyto-zoa
E. bienusi

5. V. PROTOZOA
Unicellular, chemoheterotrophic, eukaryotic organisms of kingdom Protista ( mm).
Protozoan means “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).

6. V. PROTOZOA (Continued)
Nutrition
Most are heterotrophic aerobes. Intestinal protozoa can grow anaerobically.
Some ingest whole algae, yeast, bacteria, or smaller protozoans. Others live on dead and decaying matter. Parasitic protozoa break down and absorb nutrients from their 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 an anal pore.

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

8. Protozoan classification
The groups are:
flagellates (or Mastigophora)
amoebae (or Sarcodina)
sporozoans (or Sporozoa, Apicomplexa) and
ciliates (or Ciliophora).

9. Kingdom Animalia
Subkingdom Protozoa
Phylum Sarcomastigophora
Phylum Apicomplexa
Phylum Ciliophora
Phylum Microspora
Subkingdom Metazoa
Phylum Nematoda
Phylum Platyhelminthes

10. Protozoa as Human Parasites
Taxonomy:
Kingdom: Protista
Genera:
Subphylum:
Phylum:
Trypanosoma, Leishmania, Giardia, Trichomonas
Mastigophora (mastigo = whip = flagellates)
Sarcomastigophora
Entamoeba, Naegleria, Acanthamoeba
Sarcodina (amoebae)
Plasmodium, Toxoplasma, Cryptosporidium, Isospora
Apicomplexa
Balantidium
Ciliophora

11. 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

12. Protozoa
.“eukaryote”..has genetic material encased in a nuclear membrane (unlike bacteria and viruses)
..classified traditionally by morphology (eg. organelles of locomotion), life cycle and mechanisms of reproduction etc.

13. Mastigophora: movement with flagella - e.g. Trichomonas, Giardia
Sarcodina: pseudopodia, e.g. Entamoeba histolytica
Apicomplexa: apical complex, no locomotor apparatus;
sexual reproduction, e.g. cryptosporidium, malaria, toxoplasma
Ciliophora: movement with cilia, e.g. Balantidium.

14. 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 bütschlii
Chilomastix mesnili
Trichomonas hominis
Blastocystis hominis

15. Sarcodina: (**=pathogenic) Entamoeba histolytica**
Entamoeba dispar 
Iodomoeba butschlii Dientamoeba fragilis** Endolimax nana   Entamoeba coli Entamoeba hartmani

16. Entamoeba histolytica (amoebiasis)
Phylum Sarcomastigophora.
Subphylum - Sarcodina: pseudopodia,
Life Cycle                          

18. Biology Two morphological stages occur;
Trophozoite - metabolically active invasive stage, moves with pseudopodia, ingests RBC, lives in  colon and is found in fresh diarrheal stool;
divides by binary fission.
Trophozoite µm
cogwheel distribution of nuclear chromatin
Hematophagous
unidirectional movement with pseudopodia

19. Cyst - "vegetative" inactive form resistant to 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 µm
chromotoidal body        

20. Adaptations
Cyst: a dormant form characterized by a hardened external covering in which metabolic activity has ceased.
Form in response to nutrient deficiency, drought, and decreased oxygen concentration, or pH or temperature changes.
Emerge when conditions improve

21. Contractile vacuole An organelle that expels fluid from the cell.
Freshwater organisms are usually hypertonic relative to their environment so water continually diffuses into them.
To maintain homeostasis, it must use contractile vacuole to rid cell of excess water.

22. 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

23. Diagnosis:
- stool examination - for trophozoites and cysts - amoebic serology - abscess aspirate  - Entamoeba dispar  a non-pathogen is indistinguishable by microscopy and is a much more common intestinal protozoan than Entamoeba histolytica. Antigen capture and PCR tests can distinguish E. dispar from E. histolytica in heavier infections.            

24. Treatment: Invasive states (Dysentery, Liver abscess): metronidazole
Carrier states: diiodoquine, diloxanide furoate, or paromomycin

25. Other Sarcodina

26. Phagosytosis