Amoebiasis (patient information)
Amoebiasis On the Web
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. ; Assistant Editor(s)-in-Chief: Alexandra M. Palmer
Amoebiasis is an infection of the intestines caused by the parasite Entamoeba histolytica.
What are the symptoms of Amoebiasis?
Usually, the illness lasts about 2 weeks, but it can come back if treatment is not given. Mild symptoms:*Abdominal cramps
- Intestinal gas (excessive flatus)
- Rectal pain while having a bowel movement (tenesmus)
- Unintentional weight loss
- Abdominal tenderness
- Bloody stools
Note: In 90% of people with amoebiasis there are no symptoms.
What causes Amoebiasis?
Entamoeba histolytica can live in the large intestine (colon) without causing disease. However, sometimes, it invades the colon wall, causing colitis, acute dysentery, or long-term (chronic) diarrhea. The infection can also spread through the blood to the liver and, rarely, to the lungs, brain or other organs. This condition can be seen anywhere in the world, but it is most common in tropical areas with crowded living conditions and poor sanitation. Africa, Mexico, parts of South America, and India have significant health problems associated with this disease. Entamoeba histolytica is spread through food or water contaminated with stools. This is common when human waste is used as fertilizer. It can also be spread from person to person -- particularly by contact with the mouth or rectal area of an infected person.
Who is at highest risk?
Risk factors for severe amoebiasis include:
- Old age
- Recent travel to a tropical region
- Use of corticosteroid medication to suppress the immune system
In the United States, amoebiasis is most common among those who live in institutions and people who have anal intercourse.
Examination of the abdomen may show liver enlargement or tenderness in the abdomen. Tests include:
- Blood test for amoebiasis (serology)
- Examination of the inside of the lower large bowel (sigmoidoscopy)
- Microscope examination of 3 stool specimens several days apart
When to seek urgent medical care?
Call your health care provider if you have persistent diarrhea.
Prevention of Amoebiasis
When traveling in tropical countries where poor sanitation exists, drink purified or boiled water and do not eat uncooked vegetables or unpeeled fruit. Public health measures include water purification, water chlorination, and sewage treatment programs. Safer sex measures, such as the use of condoms and dental dams for oral or anal contact, may help prevent infection.
Oral antiparasitic medication is the standard treatment for amoebiasis. The choice of drug depends on the severity of the infection. Typically oral metronidazole is used for 10 days. If you are vomiting, you may need treatment through a vein (intravenous) until you can tolerate medications by mouth. Antidiarrheal medications are usually not prescribed because they can make the condition worse. After treatment, the stool should be rechecked to ensure that the infection has been cleared.
Where to find medical care for Amoebiasis?
Directions to Hospitals Treating Amoebiasis
What to expect (Outlook/Prognosis)?
The outcome is usually good with treatment.
- Liver abscess
- Medication side effects, including nausea
- Spread of the parasite through the blood to the liver, lungs, brain, or other organs