Giardiasis is an infection of the small intestine with the parasite Giardia duodenalis, caught from contaminated water, food or close contact, such as in daycare. It causes diarrhea with bloating and gas that can drag on for weeks and lead to weight loss.
Key symptoms
- Watery or greasy, foul-smelling stools
- Bloating, gas and abdominal cramps
- Nausea and sulfur-smelling burps
- Fatigue and weight loss
- Little or no fever and no blood in the stool
What you find on exam
- Mild abdominal distension and tenderness
- Signs of dehydration, mostly in children
- Weight and growth check
- Ask about hiking, stream water, travel, daycare and pets
Tests
- Stool antigen test or stool PCR panel for Giardia
- Stool ova and parasites exam, which is less sensitive
- Electrolytes if dehydrated
- Blood or high fever points to another cause
Treatment basics
- Tinidazole single dose, nitazoxanide for 3 days, or metronidazole for 5 to 7 days
- Oral fluids, and IV fluids if dehydrated
- Avoid dairy for a few weeks if lactose intolerance follows
- Handwashing; boil or filter outdoor water
Red flags
- Signs of dehydration in a child
- Blood in the stool or high fever
- Ongoing weight loss or poor growth
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations. Written by Making Synapses. Making Synapses is not affiliated with these organizations.