Amoebiasis is a common cause of diarrhoea in infants in low-income countries and an emerging sexually transmitted infection in some developed countries. Amoebiasis also causes colitis that can present with diarrhoea and/or dysentery that can be acute or last more than 1 week. Abdominal tenderness and weight loss are common with amoebic colitis.
Amoebic liver abscess presents with right upper quadrant pain. May not present with diarrhoea, but will usually have a preceding history of diarrhoea.
Rare cause of brain abscess.
Most patients will have travelled to or resided in an endemic area in the 12 months preceding presentation. Oral-anal sexual contact is a risk factor for sexual transmission.
Diagnosis is confirmed by detection of Entamoeba histolytica antigen or DNA in stool or antibodies against the parasite in serum.
Treatment is with nitroimidazoles (including metronidazole or tinidazole) followed by luminal agents such as paromomycin or diloxanide furoate to prevent relapse. Reinfection is common in endemic regions; patients should be counselled on how to reduce the risk of reinfection.
Amoebiasis is caused by the parasite Entamoeba histolytica. It causes diarrhoea and colitis. Spread of infection from the intestine can result in liver abscess (via haematogenous dissemination). Extension from liver abscess can lead to pleural and pericardial effusion. Rarely, brain abscess may occur.
History and exam
Key diagnostic factors
- presence of risk factors
Other diagnostic factors
- generalised abdominal pain
- right upper quadrant abdominal pain
- weight loss
- altered mental status or limb weakness
- guarding and rebound tenderness of the abdomen
- right lung decreased air entry and percussion note
- exposure in endemic areas
- institutionalisation of intellectually disabled people
- men who have sex with men
- oral-anal sexual contact
- HIV infection, past or current syphilis infection
- male sex
1st investigations to order
- stool antigen detection
- PCR or qPCR of stool or liver abscess pus for E histolytica DNA
- serum antibody test
Investigations to consider
- stool microscopy
- liver ultrasound
- CT liver/chest/head
- MRI brain
Koji Watanabe, MD, PhD
AIDS Clinical Center
National Center for Global health and Medicine
KW is an author of a number of references cited in this topic.
Dr Koji Watanabe would like to gratefully acknowledge Dr William A. Petri, a previous contributor to this topic. WAP is a consultant for TechLab, Inc. which manufactures diagnostic tests for amoebiasis and is also the author of a number of references cited in this topic.
Ran Nir-Paz, MD
Senior Lecturer in Microbiology and Medicine
Department of Clinical Microbiology and Infectious Diseases
Hadassah-Hebrew University Medical Center
RNP declares that he has no competing interests.
Christopher Huston, MD
Assistant Professor of Medicine
Division of Infectious Diseases
University of Vermont College of Medicine
CH declares that he has no competing interests.
- Infectious diarrhoea
- Ulcerative colitis
- Pyogenic liver abscess
- Interim public health operational guidelines for amoebiasis (Entamoeba histolytica)
Amoebic dysentery: preventionMore Patient leaflets
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