Class Sarcodina

Phylum Protozoa – General Characteristics Unicellular animals Digestion: Intracellular digestion Excretion: By contractile vacuoles (No contractile vacuoles in marine and parasitic protozoa) Respiration: Diffusion Reproduction: * Asexually: Budding, Binary and multiple fission, Sporogony                            * Sexually   : Conjugation, Gamete formation Cyst: Unfavourable conditions - Protozoa covered by cyst (Encystment)           Favourable conditions      - Protozoa comes out of cyst (Exystment)
Class Sarcodina - Locomotory organs: Pseudopodia
1) Entamoeba histolytica		Morphology: 1) Trophozoite stage 2) Pre-Cystic Stage 3) Cystic Stage – Quadrinucleate cyst (during passage through alimentary canal) * Trophozoite has ectoplasm and endoplasm. Endoplasm has RBC.		Lifecycle: Monogenetic  (requires only one host man) Infective cysts are ingested by contaminated food, water (indirect or contaminative transference). Also person to person contact. Cysts (infective stage) swallowed àPass into stomach (resistant to gastric juice) à Intestine (Excystment by tyrosine) à Precystic stage passes into colon (They multiply by binary fission) * Under certain conditions precystic changes into trophozoite which invade the colonic epithelium using their protolytic and cytotoxin enzymes)  à Trophozoite (pathogenic stage) penetrates and enters into hepatic portal vein and enters into the liver and causes hepatic and intrahepatic abscesses. à Under certain conditions trophozoites comes out of the intestinal wall and changes into cysts (quadrinucleate form) which passes out of the host with feces.				Diagnosis: Sigmoidoscopy Stool examination for cysts and precystic forms		Disease: Amoebiasis
2) Entamoeba coli		Morphology: Harmless commensal Endoplasm has only bacteria or other substances but no RBC. Immature cyst – 4 nuclei Mature cyst – 8 nuclei		Life cycle: Same as E. histolytica Remains as lumen commensal without tissue invasion and is non-pathogenic.
3) Entamoeba gingivalis		Morphology: Harmless commensal in the gum of man. Endoplasm has bacteria and other substances but no RBC.		Life Cycle: Transmission: During kissing. No need of cyst. Transference is called direct or contagious.

Class Flagellata

Class Flagellata – Locomotory organ: Flagella, Reproduction only asexual by longitudinal binary fission.

4) Giardia lamblia

Morphology:Exists both as trophozoite and cystBilaterally symmetrical. Have 2 nuclei. Have 4 pairs of flagella (Ant. Post. Caudal. Ventra)

Life cycle: (Same as E.histolytica) Have 2 major stages in life cycle. Ingested with contaminated water. Less commonly through food or oral fecal way. Cysts ingested àBy exposure to acidic environment of stomach, the cysts excysts into trophozoite in the proximal small intestine. àTrophozite replicates in small intestine where it causes symptoms of diarrhea and malabsorption. àAfter biliary exposure some of the trophozoites form cysts in the jejunum and are passed in the feces.

Diagnosis: Both cysts and trophozoites can be found in stool examination.

Disease:Causes small intestinal disease with diarrhea. Causes Giardiasis. Prevention – Same as E. histolytica

5) Trichomonas vaginalis

Morphology: TV has only trophozoite stage. It is oval as well as flagellated.Slightly larger than WBC. 5 flagella arise near the cytostome. Reproduction occurs every 8-12 hrs by binary fission. TV dies in water.

LifeCycle: Modes of transmission – During sex. In women - In cells of vagina and urethra. In males    - In urethra Infective stage: Trophozoite Pathogenetic stage: Trophozoite

Diagnosis: Upto half of infected males and females are aymptomatic. Incubation period: 3 to 21 days. Women may notice: unusual vaginal discharge. Males may notice: A discharge from the penis – May be thin and whitish. Pain during unination. Inflammation of foreskin or glands. (less common) * Using a swab to take samples from vagina or urethra. * Immunological method: Direct immunofluorescent antibody staining.

Disease:Trichomoniasis. Treatment: Taking antibiotic tablets. Metronidazole.

6) Trichomonas hominis

Morphology: Cosmopolitan in its distribution. Lives as commensal. Numbe of flagella in trophozoite is five. Trichomonads swim in wobbly movement.

Life Cycle: Do not have cystic stage. Found in a wide host range including non-human primates, cats, dogs and various rodents.

Diagnosis: In a fresh stool, the flagellates move very rapidly in jerky non directional manner. Axostyle and undulating membrane are diagnostic. Flagellates are difficult to stain.

7) Genus Leishmania

Morphology: Leishmania is found in 2 forms. 1) Leishmanial orAmastigote form. Occurs in vertebrate hosts such as human, dogs or rodents. Oval covered of delicate cell membrane. Near nucleus there is kinetoplast (blepharoplasty and parabasal body) 2) Leptomonad or promastigote form. Found in gut of sand fly. a) Long, slender and spindle shaped. b) Nucleus is centrally placed. c) Parabasal body, blepharoplasty and axoneme lie near the anterior end. d) axoneme is continued as a long flagellum. e) Vacuole near anterior end.

Life cycle: It is digenetic. Primary host – Vertebrate Secondary host – Sand fly phlebotomus or Lutzomyia. Infected female sand fly àLeishmanial forms infect macrophages and reticuloendothelial cells à Changes into promastigote form à Multiply by binary fission until the cell ruptures à Then they invade the fresh cells (some are destroyed by neutrophils and monocytes) à The ruptured or free forms are transferred into the gut of the sand fly during its bite along with blood. à In the midgut of the sandfly changes into leptomonad form (i.e. gets elongated and flagellated) à They multiply by binary fission and large number of flagellates are formed which migrate towards pharynx and ultimately reach salivary glands. Cycle is completed when the sand fly bites another vertebrate.

Diagnosis: Donovan bodies may be found in blood or in bone marrow smears or lymphoide, liver or spleen. By indirect immunofluorescence and haemagglutination.

Disease: 3 Major types of Leishmaniasis 1) Visceralleishmaniasis (kala azar) – Caused by L. Donovani 2) Cutaneous leishmaniasis of the new world. 3) Cutaneous leishmaniasis of the old world. – Caused by L. Tropica

Class Sporozoa

Class Sporozoa – No locomotory organs. All are parasites, cilia and flagella maybe present only in sex cells. No digestive organelles and contractile vacuoles. Has sexual and asexual reproduction.                                Asexual by sporogony and schizogony. Sexual by gamete formation.
8) Genus Plasmodium	Morphology: 4 types of plasmodium which causes different types of malaria. 1) P. Vivax - Benign tertian fever 2) P. Malaria - Quartan malaria 3) P. Falciparum – Sub tertian fever 4) P. Ovale – Mild tertian fever				Life Cycle: Transmission: Inoculative transference Female anopheles bites man àParasite goes into blood with its saliva àMinute sickle shaped sporozoite in the blood àAfter about half an hour the sporozoites enter liver cells and begin schizogony 1) Pre erythrocytic schizogony Sporozoites feed on glycogen àForm large and rounded schizonts àSchizont divides by multiple fission (schizogony) into 1000 small elongated merozoitesàThey attack RBC or liver cells. * If they attack liver cells then pre erythrocytic schizogony restarts. The time taken from sporozoite to reappear as merozoite into blood again is about 10 days (This is incubation period). 2) Erythrocytic schizogony Merozoite which attack RBC feed on amino acids of haemoglobin and becomes large and round in shape. àVacuole appears. Pushes its nucleus to one side (Called ring shaped trophozoite) àgrows and becomes amoeboid in shape and shows amoeboid movement (called amoeboid schizont) àEnlarges in size (mature schizont) àThe nucleus of schizont divides into 12-24 nuclei, each becomes erythrocytic merozoite. At center poisonous substance (haemozoin) accumulates. * Life cycle can continue for many generations. * After several generations of schizogony, some merozoites grow into large   cells inside erythrocytes. They form 2 types of cells – Gametocytes. Female gametocytes – Macrogametes with small excentric nucleus. Male gametes – Microgametes, clear cytoplasm with large nucleus. These gametes need cold blood. So goes into anopheles along with blood. Nucleus of microgamete divides 4-8 nucei. Flagellates form (exflagellation) The macrogametesà nucleus divides into 2 à one becomes polar body àbecomes mature macrogamete. Zygote elongates and becomes motile like a worm. This zygote is known as ookinete. àPenetrates the wall of the stomach and covered by outer stomach membrane and   this encysted zygote is called oocyst. à In oocyst, nucleus divides repeatedly to form many nuclei à Each nuclei forms a sporozoite (Sporogony). à Oocysts burst into sporozoite àGoes to saliva à cycle is completed when the anopheles bites another man.		Diagnosis: Smears of blood taken from the peripheral blood stream. Each day for 3-4 days should be checked for negative results before a patient is declared malaria free. * Indirect immunofluorescence. *  Indirect haemagglutination * Gel diffusion techniques				Disease: Malaria
9) Toxoplasma gondii	Morphology Merozoite stage It has sickled shaped of body. Front is narrow and back end is round and wide. Covered by pellicle. Large nucleus. Nutrition through microscopic openings in the pellicle. Reproduction same as plasmodium.				Life cycle: Reproductionsame as plasmodium. * Requires 2 hosts. Definitive host: Cat, sheep, pig Intermediate host: Human, some birds, mice Transmitted congenitally (through placenta) or by ingestion of cat feces contaminated food stuff. Oocysts containing sporozoites enter àRupture into sporozoites àSporozoites enter cells of mucosa àReproduction by binary fission takes place àCovered by cell membrane and forms pseudocysts. à   After destruction of infected cell, the sporozoites enter new cells à Under favourable conditions T. Gondii forms real cysts. When cysts get into body of definitive host, sporozoites when they enter the mucosa, they turn into round schizont, which begin to reproduce by schizogony. àMerozoites form à Affect new epithelial cells à After several generations, micro and macrogametes form àFertilization àZygote àForms oocyst à Inside oocyst sporogony takes place (4 sporozoites form) * Oocysts can be infective for both definitive and intermediate host.		Diagnosis: Same as plasmodium				Disease: Toxoplasmosis Can affect any organ of human body.

Class Infusoria

Class Infusoria – Locomotory ogan: Cillia. 2 nucleus types: micro and macro nucleus. Micro is reproductive and macro is vegetative. Food enter to peristome through cilia à Cytopharynx à Cytoproct Reproduction: Asexually by binary fission, Sexually by conjugation
10) Blantidium coli	Morphology: Egg shaped. Pointed at the front and round at the back. two nuclei are present : One sausage shaped macronucleus and one micronucleus.	Life Cycle: Parasite in the large intestine of man, monkeys, pig. Reproduction by transverse binary fission. Occasionally, 2 blantidia conjugation. Also forms thick walled cyst but NO multiplication takes place in cyst. Usually carried by pigs. * Life cycle identical to that of E. histolytica.	Diagnosis: Causes ulceration of the large intestine which may cause haemorrhage and diarrhea. Trophozoites rather than cysts are found in stool.	Disease: Blantidiasis