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

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