Clinical Features of Giardiasis
Giardiasis presents with a spectrum of clinical manifestations ranging from asymptomatic carriage to severe diarrheal illness with malabsorption, with the most common symptoms being diarrhea, abdominal pain, bloating, and weight loss. 1
Key Clinical Features
Gastrointestinal Symptoms
- Diarrhea - typically watery, foul-smelling, and may be greasy or contain mucus 1
- Steatorrhea (fatty stools) due to malabsorption 2, 3
- Abdominal cramps and pain 1, 4
- Bloating and flatulence 3, 5
- Nausea and vomiting 1, 4
Systemic Manifestations
- Weight loss - significant in chronic cases 2, 4
- Fatigue and malaise 6
- Failure to thrive (particularly in children) 6
Disease Course Patterns
- Acute giardiasis - sudden onset of symptoms that may last 2-6 weeks 1
- Chronic giardiasis - persistent symptoms lasting beyond 6 weeks 1, 4
- Asymptomatic carriage - occurs in approximately 50-75% of infected children 4
Special Considerations
Risk Factors for Infection
- Travel to endemic areas or developing countries 1, 4
- Consumption of contaminated water (including recreational water) 1, 4
- Day-care center attendance or employment 1, 3
- Men who have sex with men (oral-anal contact) 1, 4
- Immunodeficiency states 1, 4
Clinical Variants
- Typical symptoms in immunocompetent hosts include diarrhea, abdominal pain, and bloating 1
- More severe and prolonged symptoms may occur in immunocompromised patients 1, 4
- Post-infectious irritable bowel syndrome can develop following giardiasis 1
Diagnostic Considerations
When to Suspect Giardiasis
- Persistent diarrhea (>11 days) 1
- Recent travel to endemic areas 1
- Greasy, foul-smelling stools 2, 3
- Symptoms of malabsorption 6, 5
Testing Recommendations
- The American Gastroenterological Association (AGA) strongly recommends testing for Giardia in patients presenting with chronic diarrhea 1
- Giardia antigen tests or polymerase chain reaction (PCR) are preferred over traditional microscopy due to their higher sensitivity and specificity 1, 4
Common Pitfalls and Caveats
- Giardiasis may mimic other conditions such as irritable bowel syndrome or inflammatory bowel disease 1
- Symptoms can persist even after successful treatment of the infection 1, 5
- Multiple stool samples may be needed for diagnosis as cyst shedding can be intermittent 1, 4
- Giardiasis should be considered in patients with persistent diarrhea even without a travel history 1
- Resistance to common antigiardial medications is increasing, which may lead to treatment failures 4, 5