Cryptosporidium parvum

• Objectives

  • Classification
  • Morphology
  • Transmission
  • Clinical Presentation
  • Diagnosis
  • Treatment
• Oocyst

  Are sporulated when excreted and are therefore immediately infective
• Oocyst

  • Double walled
  • Rounded or ovoid
  • Measure 2 to 6 µm in diameter
  • Contain 4 naked bow-shaped sporozoites
  • Sometimes visible inside the oocysts
• Trophozoite

  Round or oval intracellular forms with a single prominent nucleus
• Trophozoite

  • Measure 2.0 to 2.5 µm in diameter
  • Transitional stages from sporozoites and merozoites to meronts
• Sporozoites

  Crescent or bow shaped with a prominent nucleus in the posterior third
• Sporozoites

  • Measure 4.9 by 1.2 µm
  • Anterior end slightly pointed
  • Posterior end rounded
• Even though only C. parvum infects man, about 4 main species exist
• Main species of Cryptosporidium

  • C. parvum
  • C. muris
  • C. baileyi
  • C. melagridis
• C. parvum is associated with immunosuppressed or HIV/AIDS patients
• C. parvum is a zoonotic infection
• Contact with calves may be an unrecognized cause of infection in humans
• C. parvum is associated with water-borne, childhood, and traveler’s diarrhoea
• Ingestion of oocysts occurs via the faecal-oral route
• Transmission

  Zoonotic transmission through contaminated water, hands, food, and sexual practices
• Transmission routes

  • Surface run-off water
  • Contaminated hands
  • Food
  • Water
  • Sexual practices
  • Nosocomial transmission
  • Laboratory transmission
  • Human-to-Human
• Cryptosporidiosis produces profound inflammatory and destructive pathophysiology without tissue invasion
• Heaviest infections are seen in the distal jejunum & ileum
• Infection is believed to move along the gut from the duodenum through the rectum
• Clinical manifestations of Cryptosporidiosis

  • Nausea
  • Low-grade fever
  • Abdominal cramps
  • Anorexia
  • Watery bowel movements
• In immunocompetent individuals, the infection is self-cured
• In immunocompromised individuals, diarrhoea may persist for weeks
• Extra-intestinal infections in immunosuppressed

  • Cholecystitis
  • Hepatitis
  • Pancreatitis
• Diagnosis of Cryptosporidiosis

  1. Identification of oocyst in faeces

  2. Wet prep & Staining

  3. Direct immunofluorescence

  4. Molecular / PCR

  5. ELISA

  
• Fluid replacement

  Using ORS for fluid and electrolyte replacement
• About 80 drugs were being tested without success, with Paramomycin being the most promising
• Nitazoxanide


  Currently recommended treatment for Cryptosporidiosis
• Boiling water for consumption is recommended as oocysts are not affected by chlorination