Giardiasis is caused by Giardia lamblia. Infection occurs worldwide, common in the tropics. It has two morphologic forms; cyst and trophozoite. Cysts are the infectious form and remain viable in water for up to 3 months.

Infection is by ingestion of cysts; 10 cysts are enough to establish infection. Trophozoite form attaches to duodenal and jejunal mucosa, causing inflammation. Incubation- 1 to 3 weeks

Clinical presentation

  • Diarrhea, abdominal pain, anorexia, weakness, nausea and vomiting, steatorrhea
  • Examination; abdominal distension and tenderness
  • Dehydration
  • Malabsorption

Complications

  • Stunted growth in children
  • Hypersensitivity
  • Cholecystitis, cholangitis, hepatitis- rare

Investigations

  1. Antigen detection assay- e.g., ELISA
  2. PCR- detect the organism in stool
  3. Stool microscopy- examine for cysts
  4. Duodenal or jejunal endoscopy- has a high yield
  5. String test- looks for trophozoites
  6. Jejunal biopsy- looks for the organism on the surface

Differential diagnosis

  • Cryptosporidiosis
  • Travelers diarrhea
  • Lactose intolerance
  • Crohn’s ileitis

Management

  • Tinidazole 2g stat
  • Metronidazole 400mg tds for 10 days
  • Nitazoxanide 500mg PO bd for 3 days

Prevention

  • Counseling on reducing transmission
  • Infection control
  • Water purification

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