Atrial Flagellates

• What type of flagella do organisms in the Phylum Sarcomastigophora possess for locomotion?

  Whip-like flagella
• In which subphylum are the digestive and reproductive flagellates classified?

  Subphylum Mastigophora
• What are the examples of digestive and reproductive flagellates?

  • Chilomastix mesnili
  • Dientamoeba fragilis
  • Giardia lamblia
  • Trichomonas hominis
  • Trichomonas tenax
  • Trichomonas vaginalis
• What are the examples of blood and tissue flagellates (hemoflagellates)?

  • Leishmania braziliensis
  • Leishmania donovani
  • Leishmania tropics
  • Trypanosoma cruzi
  • Trypanosoma brucei complex
• What distinguishes pathogenic flagellates from non-pathogenic flagellates?

  Pathogenic flagellates cause disease, while non-pathogenic flagellates are commensals.
• Which pathogenic flagellate is known to cause diarrhea?

  Giardia lamblia
• Which pathogenic flagellate can produce vaginitis and urethritis?

  Trichomonas vaginalis
• What are the non-pathogenic flagellates mentioned in the study material?

  • Trichomonas hominis
  • Trichomonas tenax
  • Chilomastix mesnili
• What is unique about Dientamoeba fragilis despite its name?


  It is not an amoeba but an intestinal flagellate.
• What stage of Dientamoeba fragilis is known to exist?

  Only the trophozoite stage is known.
• How was Dientamoeba fragilis originally classified?

  It was originally described as an amoeba.
• What morphological feature does Dientamoeba fragilis share with Trichomonas?

  It resembles Trichomonas morphologically.
• What is the mode of transmission for Dientamoeba fragilis?

  Fecal-oral route via contaminated food or water.
• What can be a co-infection with Dientamoeba fragilis?

  Enterobius vermicularis.
• Why are infections with Dientamoeba fragilis often asymptomatic?

  It does not invade tissues like E. histolytica.
• What symptoms can chronic infections of Dientamoeba fragilis mimic?

  Chronic infections may mimic irritable bowel syndrome (IBS).
• What are the diagnostic methods for Dientamoeba fragilis?

  • Observation of binucleate trophozoites in stool
  • Microscopy and direct fecal smear
  • Purged stool examination
  • Fixatives: PVA + Schaudinn’s fixatives
• What is the treatment for Dientamoeba fragilis?

  Iodoquinol
• What are the key structures associated with flagellates?

  • Flagellum/Flagella: locomotor apparatus
  • Kinetoplast: provides energy
  • Cytostome: cell mouth
  • Undulating membrane: aids in motility
  • Axostyle: support in locomotion
  • Costa: rib-like structure for support
• What was the initial name given to Giardia lamblia?

  Cercomonas intestinalis
• What is the habitat of Giardia lamblia in humans?

  Duodenum, jejunum, and upper ileum
• How is the trophozoite of Giardia lamblia described morphologically?

  It is pear/tear drop shaped and bilaterally symmetrical.
• What is the significance of the ventral sucking disc in Giardia lamblia?

  It is a pathogenic determinant that aids in attachment.
• What is the infective stage of Giardia lamblia?

  Mature cysts
• How does Giardia lamblia undergo excystation?

  It occurs in the duodenum after ingestion of mature cysts.
• What happens to Giardia lamblia as feces dehydrates?

  It undergoes encystation.
• What are the diagnostic stages of Giardia lamblia?

  The cyst and trophozoites.
• What is the primary pathogenicity mechanism of Giardia lamblia?

  It attaches to intestinal villi causing mechanical irritation.
• What are the symptoms of Giardiasis?

  It can cause diarrhea, malabsorption, and abdominal pain.
• What is the average onset time for Giardiasis symptoms?

  Between 1 to 4 weeks, with an average of 9 days.
• What are the laboratory tests used for diagnosing Giardiasis?

  • Direct fecal smear
  • Entero test/Enterotube test/string test
  • Aspirate and biopsy
  • Antigen detection test
• What is the drug of choice for treating Giardiasis?

  Metronidazole
• What are some preventive measures for Giardiasis?

  Proper disposal of human excreta and access to clean drinking water.
• What type of stools may indicate a Giardia infection?

  Greasy, frothy stools that may float on toilet water
• What specimens are used for diagnosing Giardia?

  • Stool
  • Duodenal contents
• What are the diagnostic stages of Giardia?

  Trophozoite and Cyst
• What laboratory tests are used for diagnosing Giardia?

  1. Direct Fecal Smear

  • Falling leaf-like motility observed

  1. Entero test/Enterotube test/String test/Beale String's test (non-invasive)

  • Gelatin capsule swallowed with nylon string

  1. Aspirate and Biopsy (invasive)
  2. Antigen detection test and immunofluorescence commercial test kit

  • Cyst wall protein 1 – Giardia antigen found in stool
• What is the drug of choice for treating Giardia?

  Metronidazole
• What are alternative treatments for Giardia?

  • Tinidazole
  • Albendazole
  • Furazolidone
  • Quinacrine
  • Paromomycin
• What are the prevention and control measures for Giardia?

  • Proper disposal of human excreta
  • Improve access to clean and safe drinking water
  • Good food preparation practices
  • Avoid using "night soil"
  • Health education and promotion