Crypto

• Cryptosporidium spp.


  Infects humans (opportunistic) and other animals

  
• Cryptosporidium spp.


  • Intracellular, extracytoplasmic (brush borders)

  
• Transmission of Cryptosporidium spp.


  Ingestion of thick-walled oocysts from the environment, pets, and farm animals

  
• Species of Cryptosporidium


  • Cryptosporidium hominis (mainly in humans)
  • Cryptosporidium parvum

  
• All stages of development of Cryptosporidium spp. are completed in the gastrointestinal tract of the host

  
• Life Cycle of Cryptosporidium spp.


  1. In the small intestine, the microgamete fertilizes the macrogamete producing a zygote that immediately develops to become sporulated oocyst (diagnostic and infective stage)

  2. Thin-walled oocyst can easily burst inside the small intestine, releasing sporozoites → internal autoinfection

  3. Thick-walled oocyst does not easily burst; thus it will be passed in the feces

  4. When ingested, the oocyst releases 4 sporozoites which infects intestinal cells

  5. Inside the intestinal cells, it undergoes Schizogony for 2 cycles producing merozoites

  6. Some merozoites mature to become micro- and macrogamete which then produces oocyst and the cycle continues

  
• Asexual (Schizogony)


  Mature oocyst (containing 4 sporozoites → sporozoites invade intestinal epithelium → trophozoite → merozoites)

  
• Sexual (Sporogony)


  • Some merozoites develop into macro- and microgametocytes (gametogony) → zygote
  • Thin-walled oocyst: Autoinfetion → chronic infection
  • Thick-walled oocyst: passed out with feces
• Pathogenesis of Cryptosporidiosis


  • Immunocompetent: Asymptomatic to self-limited watery diarrhea (MC symptom) in immunocompetent individuals (2 – 3 weeks), Pain, anorexia, fever, nausea, and weight loss
  • Immunocompromised: Severe chronic diarrhea (AIDS patients), Also at risk; Children in day care centers, animal handlers, health care workers, Diarrhea >2 weeks, dehydration, abdominal pain, anorexia, fever, nausea, vomiting, weight loss, malabsorption

  
• Extra-intestinal manifestations of Cryptosporidiosis

  • Heavy infection of bile duct and gallbladder → acute gangrenous cholecystitis
  • Pulmonary: dyspnea, chronic cough, bronchiolitis, pneumonia
  • Possibly, conjunctivitis
• Oocyst of Cryptosporidium


  Round, 4 – 6 um, Contain 4 crescent-shaped sporozoites, Infective stage

  
• Diagnostic methods for Cryptosporidium


  • Sheather's sugar flotation technique
  • Formalin Ether/Ethyl acetate concentration technique
  • Kinyoun's modified acid-fast staining: oocyst from stool
  • Intestinal biopsy
• Kinyoun's modified acid-fast staining


  Quickest and cheapest, Appearing red-pink doughnut-shaped circular organisms in a blue background, Where oocysts are best identified
• Treatment for Cryptosporidiosis


  • Hydration and symptomatic treatment
  • Nitazoxanide effective among immunocompetent patients, but unclear efficacy for immunocompromised patients
  • Promising treatment: Bovine colostrum, paramomycin, clarithromycin

  
• Prevention and Control of Cryptosporidiosis


  • Water-borne transmission: most common source
  • Proper hygiene
  • Boiling or filtering
  • Chlorination does NOT affect oocyst