Cysto

• Cystoisospora belli


  Aka Isospora belli
• Humans


  • The only known hosts
• Transmission


  1. Ingestion of mature oocyst

  2. Sporulated oocyst contains 2 sporocyst; each containing 4 sporozoites

  3. Sporulation of oocyst in food or water (external environment)

  
• Habitat


  Distal duodenum and Proximal ileum
• Life Cycle of Cyclospora belli

  1. Microgamete fertilizes the macrogamete

  2. Unsporulated oocyst passed out through the feces

  3. Unsporulated oocyst undergoes sporulation in the external environment

  4. Immature oocyst with 2 sporoblasts

  5. Mature/Sporulated oocyst with 2 sporocysts, each contain 4 sporozoites

  6. Sporulated oocyst is ingested by the human host

  7. In the stomach, oocyst lyses, releasing sporozoites

  8. Sporozoites infect intestinal cell where it undergoes schizogony to produce and release merozoites

  9. Merozoites infect another intestinal cells to undergo several cycle of schizogony

  10. Some merozoites differentiate to form the microgamete and macrogamete

  
• Asexual (schizogony)


  Mature oocyst (containing 2 sporocysts, each with 4 sporozoites) when ingested release sporozoites invading intestinal cells of small intestine → trophozoites → merozoites

  
• Sexual (sporogony)


  Some merozoites develop into macro- and microgametocytes → zygote → oocyst which are passed out with feces and undergo maturation in the environment
• Pathogenesis


  • Generally asymptomatic, especially in immunocompetent individuals
  • More common in children and immunocompromised patients (AIDS, cancer like lymphoma, leukemia, and organ transplant patients
  • Cystoisosporiasis Manifestations: Prolonged mild diarrhea, abdominal pain, fever, malaise, flatulence, malabsorption syndrome with weight loss, dissemination of parasites to other organs in AIDS patients
• Oocyst of C. belli / I. belli


  • Immature Oocyst: Elongate and ovoidal, 20 – 33 um x 10 – 19 um, contains embryonic element
  • Immature Oocyst with two Sporoblasts
  • Mature with Sporocysts: Sporocysts with 4 long and slender sporozoites each
• Diagnosis


  1. Visualization of oocyst in fecal specimens: Direct Fecal Smear (DFS), Concentration Technique

  2. Acid-fast stain

  3. Entero-test (string capsule) and duodenal aspirate if stool is negative and high index of suspicion

  4. Eosinophilia in the blood and Charcot-Leyden crystals in stool
• Microgamete


  The gamete with a lot of bigger granules
• Macrogamete


  The gamete that is devoid of big granules
• Prevention and Control


  • Proper hygiene
  • Food and water precaution
  • Proper human waste disposal