4. PROTOZOA - flagellate & cilliates

• The number of nucleus found in mature cyst of E. histolytica is 8
• Ingested RBC usually found in the E. histolytica trophozoites
• The life cycle of E. coli is same as E. histolytica except that it remains a luminal commensal without tissue invasion
• A chromatoid body is a clump of genetic material found in the nucleus of amoebae
• Parasitic form


  Sensitive to environmental changes and it disintegrates rapidly upon release from the body
• Morphological forms of Naegleria fowleri

  1. Trophozoite

  2. Cyst

  3. Flagellate
• Peripheral nuclear chromatin is absent in

  • Trophozoite
  • Cyst
• Free living amoeba include

  • Naegleria
  • Acanthamoeba
• Diseases caused by Acanthamoeba spp.

  • Keratitis
  • Granulomatous amoebic encephalitis
• Protozoa: Intestinal and atrial flagellates and ciliates

  
• Entamoeba histolytica


  • Found in colon, liver and lungs
• Giardia lamblia


  • Found in small intestine
• Trichomonas vaginalis


  • Found on mucous membranes of vagina
• Balantidium coli


  • Found in colon
• Cryptosporidium parvum, Cyclospora cayetanensis, Sarcocystis species


  • Found in intestine
• Plasmodium species


  • Found in blood
• Toxoplasma gondii


  • Found in tissue
• Sarcomastigophora


  Phylum containing intestinal amoeba, free living amoeba, and intestinal and atrial flagellates and ciliates

  
• Microsporidia


  Phylum containing intestinal and atrial flagellates and ciliates
• Intestinal Amoeba


  • Entamoeba histolytica
  • Entamoeba coli
  • Endolimax nana
  • Iodamoeba butschlii
  • Blastocystis hominis
• Free living Amoeba


  • Naegleria fowleri
  • Acanthamoeba spp.
• Intestinal and atrial flagellates and ciliates

  • Giardia lamblia
  • Dientamoeba fragilis
  • Trichomonas vaginalis
  • Balantidium coli
• Blood and tissue flagellates

  • Leishmania spp.
  • Trypanosoma spp.
• Blood and tissue sporozoa

  • Plasmodium vivax
  • Plasmodium ovale
  • Plasmodium malariae
  • Plasmodium falciparum
  • Plasmodium knowlesi
  • Babesiosis
  • Toxoplasma gondii
  • Pneumocystis carinii
• Giardia lamblia


  Pear shape and 8 flagella, Length: 9-21 mm, Width: 5-15 mm, Bilaterally symmetrical, 2 nucleus, One on either side of axostyle, Fine granular cytoplasm, 2 median parabasal body (look like mustache)
• Giardia lamblia cyst


  Oval and lightly bile-stained, Diameter 8-12 μm, 4 nucleus (mature), Small eccentric karyosome, Clear space beneath the thin cyst wall
• Life cycle of Giardia lamblia

  1. Ingestion of cysts in contaminated water, food, or by the fecal-oral route

  2. In the small intestine, excystation releases trophozoites

  3. Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal small bowel where they can be free or attached to the mucosa

  4. Encystation (trophozoites multiply) occurs as the parasites transit towards the colon

  5. The cyst is the stage found most commonly in nondiarrheal faeces

  
• Giardiasis


  Inflammation due to Giardia
• Giardia lamblia


  • Inhabit glandular crypts of mucosa layer in duodenum and jejunum
  • Attach to epithelial surface of mucosa layer
  • Sometimes disrupt intestinal function → malabsorption → weight loss and steatorrhea (excessive amount of fat in the faeces)
• Malabsorption of fat


  Acute diarrhea and abdominal pain (high fat content in stool)
• Some patients asymptomatic, some patients have general symptoms (fever, anaemia, allergy)
• Laboratory diagnosis of Giardia lamblia

  • Stool (macroscopic, microscopic examination)
  • Duodenal fluid (microscopic examination)
  • Serum (serology test)
• ELISA


  An enzyme is used when the enzyme and the antigen-antibody complex bind, a color indicator or other easily recognizable sign occurs
• Stool examination for Giardia lamblia


  • Direct wet mount (saline and iodine) - detection of motile trophozoites, Permanent staining (Kohn, Trichrome) - detection of cysts, Concentration technique and permanent stain smear - detection of cysts in formed stool, Examination of triple fecal test ± examination of 3 stool specimens from nonconsecutive day
• Serology test not useful in diagnosis as antibody might be present due to past infection