Cyclo

• Cyclospora cayetanensis


  Originally called cyanobacterium-like body (CLB), photosynthesizing organelles and autofluorescence particles characteristic of blue green algae
• Further studies reveal that this is a coccidia
• Transmission


  Ingestion of Mature oocyst with 2 sporocysts and 2 sporozoites each, total of 4 sporozoites
• Habitat


  Small intestine, with jejunum as predilection
• Life Cycle of Cyclospora cayetanensis


  1. In the small intestine, the microgamete fertilizes macrogamete forming unsporulated oocyst (diagnostic stage) that is passed in the feces

  2. It will undergo complete sporulation in warm environment for 7 – 12 days producing a mature oocyst

  3. The mature/sporulated oocyst (infective stage) will contaminate the food and will later be ingested by the human host

  4. Inside the host, the sporulated oocyst reaches the small intestine and excysts releasing sporozoites which will infect other cells or undergoes the 2 cycle of merogony

  
• Asexual (schizogony)


  Mature oocyst (containing 2 sporocysts, each with 4 sporozoites) when ingested release sporozoites invading intestinal cells of small intestine: Jejunum → meronts I (8 – 12) → meronts II (4)
• Sexual (sporogony)


  Some merozoites develop into macro- and microgametocytes → zygote → unsporulated oocyst with feces → maturation in warm environment
• Pathogenesis


  • Generally, self-limiting for immunocompetent individual
  • Immunity w/ repeated infections
  • Resolves without treatment
• Initial symptoms are malaise, low grade fever (12 – 24 hours post exposure)
• Chronic, intermittent watery diarrhea alternating with constipation

  Diarrhea for 6 – 7 weeks, >6 stools/day
• Other symptoms


  • Fatigue
  • Anorexia
  • Weight loss
  • Nausea
  • Vomiting
  • Abdominal pain
  • Flatulence
  • Bloating
  • Dyspnea
• 1. xylose malabsorption: proximal small intestine malabsorption
• NO DEATHS reported
• Diagnosis


  • Direct microscopic examination
  • Concentration technique
  • Acid-fast staining (Kinyoun' stain)
  • Oocyst: autofluorescent (Fluorescent microscopy: Blue or green circles)
  • Polymerase chain reaction (Performed in capable centers)
• Treatment


  • Self-limiting: Treatment is NOT necessary if symptoms are mild
  • Trimethoprim-sulfamethoxazole (160/800 mg tab BID x 7 days) is the only proven drug if treatment is warranted
• Prevention and Control


  • Good sanitary practices
  • Adequate water treatment (Boiling water, Chlorination is not effective)
  • Proper washing of fruits and vegetables (Raspberries in Guatemala, Lettuce and basil-pesto salad in Peru and Nepal)