Amebiasis is an infection with the parasite Entamoeba histolytica, spread through food or water contaminated with stool, most often in low-resource countries. It can cause colitis with bloody diarrhea, and the parasite can travel to the liver to form an abscess.
Key symptoms
- Diarrhea with blood and mucus that builds over 1 to 3 weeks
- Abdominal pain and cramps
- Fever and weight loss
- Right upper abdominal pain and fever with liver abscess, often without diarrhea
- Recent travel to or life in an endemic area
What you find on exam
- Abdominal tenderness, mostly in the lower abdomen
- Tender, enlarged liver with liver abscess
- Hydration status and vital signs
- Signs of peritonitis from perforation
Tests
- Stool antigen test or PCR for E. histolytica (microscopy cannot tell it from harmless species)
- Serology, especially for liver abscess
- Ultrasound or CT of the liver for abscess
- Blood count and liver tests; colonoscopy with biopsy in unclear cases
Treatment basics
- Metronidazole or tinidazole for colitis or liver abscess
- Then a luminal agent such as paromomycin to clear cysts from the gut
- Luminal agent alone for people with cysts and no symptoms
- Fluid and electrolyte replacement
- Drain a liver abscess only if large, about to rupture or not responding
Red flags
- Severe abdominal pain with rigidity: perforation or toxic megacolon
- Liver abscess with sudden pain, shortness of breath or shock: rupture
- Severe dehydration or signs of sepsis
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; CDC, Hand Hygiene in Healthcare Settings. Written by Making Synapses. Making Synapses is not affiliated with these organizations.