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