🔬 328.1 · Giardia duodenalis (Giardiasis)

Nelson Textbook of Pediatrics 22nd Edition | Giardia duodenalis (also G. lamblia, G. intestinalis) is the most common intestinal parasite in the United States. It causes acute or chronic diarrhea, malabsorption, greasy foul-smelling stools, flatulence, abdominal distension, and failure to thrive. Transmission: fecal-oral (waterborne outbreaks, daycare centers, travel). Diagnosis: stool antigen EIA (test of choice). Treatment: tinidazole (single dose for ≥3 years), nitazoxanide (for ≥1 year), or metronidazole. Asymptomatic carriers generally not treated except in outbreak settings.