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- Giardiasis

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
- Antigen detection assay- e.g., ELISA
- PCR- detect the organism in stool
- Stool microscopy- examine for cysts
- Duodenal or jejunal endoscopy- has a high yield
- String test- looks for trophozoites
- 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