What are the symptoms of giardia (giardiasis) infection?

Symptoms of Giardiasis

Giardiasis primarily presents with watery, non-bloody diarrhea, abdominal cramps, bloating, excessive flatulence, and weight loss, typically lasting 2-6 weeks but potentially becoming chronic. 1, 2

Primary Gastrointestinal Symptoms

• Diarrhea is the hallmark symptom—characteristically watery, foul-smelling, and may be greasy or contain mucus, but notably without blood 1, 2, 3
• Abdominal cramps and pain occur frequently, described as cramping discomfort throughout the abdomen 1, 2, 3
• Bloating and excessive gas (flatulence) are prominent features that distinguish giardiasis from other diarrheal illnesses 1, 2, 3
• Belching is commonly reported alongside the flatulence 4

Systemic and Nutritional Symptoms

• Weight loss develops due to malabsorption of nutrients, particularly in prolonged infections 1, 2, 5
• Fatigue and general malaise are commonly reported and can be debilitating 2
• Nausea and vomiting may occur, though less consistently than the diarrheal symptoms 2, 5
• Steatorrhea (fatty stools) can develop from fat malabsorption 5

Disease Course and Duration

• Symptoms typically last 2-6 weeks in acute infections 1
• The infection can become chronic and may recur even after treatment 1, 2
• Persistent symptoms beyond 14 days should raise strong suspicion for giardiasis, particularly in travelers 1, 2
• Unlike most enteritides, giardiasis may cause severe weight loss and generalized discomfort when chronic 4

Clinical Mimicry and Diagnostic Pitfalls

• Symptoms closely resemble functional diarrhea (FD) or diarrhea-predominant irritable bowel syndrome (IBS-D), making clinical distinction difficult 1, 2
• Giardiasis may mimic inflammatory bowel disease or celiac disease 2
• Symptoms alone cannot reliably distinguish giardiasis from other causes of diarrhea—laboratory confirmation is essential 1
• Post-infectious IBS can persist even after successful parasite eradication 2, 6

High-Risk Presentations

• Immunocompromised patients (especially those with HIV) experience more severe and prolonged symptoms 1
• Travelers with persistent diarrhea >14 days require specific parasitic evaluation 1, 2
• Asymptomatic carriage is equally common as symptomatic disease 2, 6

Key Risk Factors to Elicit in History

• Recent travel to endemic areas or developing countries 1, 2
• Drinking untreated water from streams or lakes (hikers, campers) 1
• Day-care center attendance or employment 1, 2
• Men who have sex with men, particularly those practicing oral-anal contact 1, 2
• Consumption of contaminated water or food 2