Highlights & Basics
- Amebiasis is a common cause of diarrhea in infants in low-income countries and an emerging sexually transmitted infection in some developed countries. Amebiasis also causes colitis that can present with diarrhea and/or dysentery that can be acute or last more than 1 week. Abdominal tenderness and weight loss are common with amebic colitis.
- Amebic liver abscess sometimes presents with right upper quadrant pain. May not present with diarrhea, but will usually have a preceding history of diarrhea. Early diagnosis is often challenging because most patients show prolonged fever without additional symptoms.
- Rare cause of brain abscess.
- Most patients will have traveled to or resided in an endemic area in the 12 months preceding presentation. Men who have sex with men and persons who engage in oral-anal sexual contact are at high risk for sexually transmitted amebiasis.
- Diagnosis is confirmed by detection of Entamoeba histolytica antigen or DNA in stool or antibodies against the parasite in serum.
Quick Reference
History & Exam
Key Factors
Other Factors
Diagnostics Tests
Treatment Options
Definition
Epidemiology
Etiology
Pathophysiology
Images
Cyst of Entamoeba histolytica: unstained (A), and iodine stained (B) after formalin-ether concentration of stool sample.
Amebic appendicitis with skin fistula two weeks after appendectomy (enhanced computed tomography).
Hematoxilin-Eosin stain (A-C) and Periodic acid-Schiff stain (D-F) of resected appendix of amebic appendicitis. Entamoebas are deeply dyed by Periodic acid-Schiff stain.
Cyst of Entamoeba histolytica: iodine stain of stool sample
Life-cycle of Entamoeba histolytica
Trophozoites of Entamoeba histolytica: trichrome stain of stool sample
Trophozoite of Entamoeba histolytica with pseudopod (red arrow): direct unstained stool sample.
Amebic ulcerations of the colon: colonic ulcers averaging 1 mm to 2 mm in diameter on gross pathology
Posterior-anterior and lateral CXR of a patient with amebic liver abscess: CXR findings include elevated right hemidiaphragm and evidence of atelectasis
Entamoeba histolytica brain abscess
Citations
Shirley DT, Farr L, Watanabe K, et al. A review of the global burden, new diagnostics, and current therapeutics for amebiasis. Open Forum Infect Dis. 2018 Jul;5(7):ofy161.[Abstract][Full Text]
Centers for Disease Control and Prevention. CDC Yellow Book 2026: health information for international travel. Section 5: travel-associated infections & diseases - post-travel diarrhea. Apr 2025 [internet publication].[Full Text]
Public Health England. Interim public health operational guidelines for amoebiasis (Entamoeba histolytica). Oct 2017 [internet publication].[Full Text]
Gonzales MLM, Dans LF, Sio-Aguilar J. Antiamoebic drugs for treating amoebic colitis. Cochrane Database Syst Rev. 2019 Jan 9;1:CD006085.[Abstract]
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