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Referral and warning signs
When to refer
Referral usually not necessary unless: Severe dehydration. Persistent symptoms despite treatment. Significant weight loss/malabsorption. Diagnostic uncertainty.
Red flags
- Severe dehydration
- Significant unintentional weight loss
- Symptoms persisting > 2-4 weeks despite treatment
Signs and symptoms
- Often asymptomatic.
- Diarrhoea: Often prolonged (>7 days), watery, greasy, foul-smelling stools (steatorrhoea). Non-bloody.
- Abdominal cramps, bloating, excessive flatulence.
- Nausea.
- Anorexia.
- Weight loss (especially if chronic/malabsorption).
- Fatigue, malaise.
Risk factors
- Drinking contaminated water (untreated surface water, wells).
- Poor sanitation and hygiene.
- Children in daycare centers.
- Travelers to endemic areas.
- Campers/hikers drinking untreated water.
- Immunodeficiency (e.g., IgA deficiency, HIV).
Diagnosis
Clinical assessment
Suspect in patients with prolonged watery/greasy diarrhoea, bloating, and flatulence, especially with relevant exposure history (contaminated water, travel, daycare). Differentiate from other causes of chronic diarrhoea and malabsorption (e.g., lactose intolerance, Celiac disease, bacterial overgrowth, Cryptosporidiosis).
Investigations
- Stool Examination (Ova & Parasites - O&P): Identification of Giardia cysts or trophozoites. Multiple samples (e.g., 3 samples on alternate days) increase sensitivity as cyst shedding is intermittent.
- Stool Antigen Detection Tests (EIA or rapid tests): More sensitive than microscopy.
- Stool PCR: High sensitivity/specificity (reference labs).
- Duodenal fluid analysis or biopsy (via endoscopy): Rarely needed, reserved for diagnostic uncertainty.
Diagnostic criteria
Identification of Giardia cysts/trophozoites or antigen/DNA in stool or duodenal fluid.
Management
Non-pharmacological management
- Maintain adequate hydration (ORS if needed, though dehydration less severe than bacterial/viral diarrhoea).
- Supportive care.
- Good hygiene practices to prevent spread.
Pharmacological treatment
- Metronidazole: 2g PO daily for 3 days (Adult); OR 250-400mg PO TID for 5-7 days (Adult). Child: 15 mg/kg/day divided TID for 5-7 days (UCG 2023 mentions 30mg/kg single dose daily for 3 days - clarification needed based on source, typical treatment is 5-7 days or 3 days high dose).
- Tinidazole: 2g PO single dose (Adult); 50 mg/kg (max 2g) single dose (Child >3 years). Often better tolerated than metronidazole.
- Nitazoxanide: Alternative agent.
- Paromomycin: Option in pregnancy (poorly absorbed).
- Treat symptomatic individuals. Treatment of asymptomatic carriers generally not recommended unless public health risk (e.g., food handler, daycare setting).
Monitoring
- Monitor for resolution of symptoms.
- Follow-up stool examination generally not needed if symptoms resolve.
Complications
- Malabsorption (fat, fat-soluble vitamins, lactose intolerance).
- Weight loss, failure to thrive (children).
- Dehydration (usually mild).
- Reactive arthritis (rare).
- Chronic fatigue (post-giardiasis syndrome - controversial).
Prevention
- Safe drinking water (boiling, filtering, chemical treatment).
- Good personal hygiene (handwashing).
- Proper sanitation/sewage disposal.
- Avoid swallowing recreational water (lakes, rivers, pools).
- Peel or cook raw fruits/vegetables in endemic areas.
Patient education
- Explain Giardia infection and faecal-oral transmission.
- Importance of completing medication course.
- Metronidazole/Tinidazole: Avoid alcohol during and after treatment.
- Hygiene measures to prevent spread to others.
- Safe water precautions if relevant.
Uganda-specific notes
Endemic protozoan infection. Consider in cases of persistent diarrhoea. Metronidazole and Tinidazole are listed treatments.
References
- Uganda Clinical Guidelines (UCG) 2023
Chapter 6, Section 6.2.4