Coccidia

• What are unicellular organisms also known as?

  Protozoans
• What characterizes the organisms under the class Sporozoa?

  They are microscopic, spore-forming, single-celled, obligate, intracellular organisms
• What is the phylum that includes the class Sporozoa?

  Apicomplexa
• What are the two types of reproduction in the life cycle of Sporozoa?

  • Sexual: Sporogony (produces sporozoites)
  • Asexual: Schizogony (produces merozoites)
• Name the parasites under the coccidian group.

  • Cystoisospora belli (Isospora belli)
  • Cryptosporidium hominis
  • Cyclospora cayetanensis
  • Toxoplasma gondii
  • Sarcocystis hominis and Sarcocystis suihominis
• What is the morphology of Cystoisospora belli oocysts?

  They are elongated ovoid and measure 25 µm x 15 µm
• What surrounds each oocyst of Cystoisospora belli?

  A thin smooth 2-layered cyst wall
• What are the two kinds of oocysts of Cystoisospora belli?

  Immature and mature cysts
• What is found in the immature oocyst of Cystoisospora belli?

  Two sporoblasts
• What happens to oocysts of Cystoisospora belli outside the body?

  They mature and sporoblasts convert into sporocysts
• How many sporozoites are contained in each sporocyst of Cystoisospora belli?

  Four crescent-shaped sporozoites
• What is the infective stage of Cystoisospora belli?

  Sporulated oocyst containing 8 sporozoites
• How is Cystoisospora belli transmitted?

  Ingestion of food and water contaminated with sporulated oocyst (fecal-oral route)
• What is the nature of coccidians?


  They are intestinal in nature
• Describe the life cycle of Cystoisospora belli.


  1. Sporulated oocyst is swallowed.
  2. 8 sporozoites are released in the small intestine.
  3. Sporozoites invade intestinal epithelial cells.
  4. Transform into trophozoites and multiply asexually (schizogony).
  5. Gametogony occurs, producing oocysts shed in feces.
• What is the diagnostic stage of Cystoisospora belli?


  Immature oocyst in the feces
• What is the typical symptom of Cystoisospora belli infection in immunocompetent individuals?


  Usually asymptomatic
• What are the symptoms of symptomatic Cystoisospora belli infection?


  Diarrhea, fever, malaise, abdominal pain, and flatulence
• Which groups are more commonly affected by Cystoisospora belli infection?


  Children and male homosexuals with AIDS
• What is a significant complication of Cystoisospora belli in AIDS patients?


  Dissemination of the parasite to other organs
• What are the diagnostic methods for Cystoisospora belli infection?


  • Direct microscopy of stool
  • Concentration techniques (sedimentation or flotation)
  • Staining techniques (Iodine, Kinyoun, Auramine-Rhodamine, Ziehl-Neelsen)
  • Enterotest and duodenal aspirate
  • Molecular testing
• What is the treatment for asymptomatic Cystoisospora belli infection?


  Bland diet and bed rest
• What is the treatment for symptomatic Cystoisospora belli infection?


  Trimethoprim-sulfamethoxazole
• What are the prevention and control measures for Cystoisospora belli?


  • Good sanitary practices
  • Thorough washing and cooking of food
  • Provision for safe drinking water
• What is the morphology of Cryptosporidium hominis oocysts?


  Spherical or oval, about 5 µm in diameter
• How do Cryptosporidium hominis oocysts stain?


  They do not stain with iodine and are only seen in acid-fast
• What are the two kinds of oocysts of Cryptosporidium hominis?


  Thin-walled oocysts (responsible for autoinfection) and thick-walled oocysts (passed out with feces)
• What do both thin-walled and thick-walled oocysts of Cryptosporidium hominis contain?


  Four crescent-shaped sporozoites
• What is the infective stage of Cryptosporidium hominis?


  Oocyst
• What is the major host for Cryptosporidium hominis?


  Cattle (Cryptosporidium parvum)
• Describe the life cycle of Cryptosporidium hominis.


  1. Oocysts are infectious when ingested.
  2. Sporozoites attach to epithelial cells of the GIT.
  3. Asexual cycle occurs.
  4. Trophozoites develop and divide (schizogony) producing merozoites.
  5. Gametocytes are produced, leading to zygote formation.
• What is the pathology of Cryptosporidium hominis in immunocompetent individuals?


  Self-limiting diarrhea within 2-3 weeks
• What are the symptoms of Cryptosporidium hominis infection in immunocompromised individuals?


  Severe diarrhea, bile duct and gallbladder infection, blunted intestinal villi, malabsorption, and excessive fluid loss
• What is a severe complication of Cryptosporidium hominis infection in AIDS patients?


  Severe form of diarrhea that is progressively worse and life-threatening
• What are the sources of infection for Cryptosporidium hominis?


  • Faulty water purification system
  • Swimming in contaminated recreational water
  • Infected food handlers
  • Nosocomial infection
• What are the diagnostic methods for Cryptosporidium hominis infection?


  • Sheather's sugar flotation
  • Zinc sulfate flotation technique
  • Formalin ether/ethyl acetate concentration technique
  • Kinyoun's modified acid-fast stain (method of choice)
  • IFA and DNA probe
• What is the treatment for Cryptosporidium hominis infection?


  No acceptable treatment yet; supportive therapy is recommended
• What is said to be effective in preliminary studies for treating Cryptosporidium hominis?


  Nitazoxanide
• What are some treatments for severe diarrhea caused by Cryptosporidium hominis?


  Bovine colostrum, paromomycin, and clarithromycin
• What are the prevention and control measures for Cryptosporidium hominis?


  • Chlorination is NOT effective
  • Use of multiple disinfectants and combined water treatment
  • Proper disposal of human and animal excreta