Amebiasis is an infection of the intestines caused by the parasite Entamoeba histolytica.
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.
Risk factors for severe amebiasis include:
- Old age
- Recent travel to a tropical region
- Use of corticosteroid medication to suppress the immune system
In the United States, amebiasis is most common among those who live in institutions and people who have anal intercourse.
Usually, the illness lasts about 2 weeks, but it can come back if treatment is not given.
- Abdominal cramps
- Passage of 3 - 8 semiformed stools per day
- Passage of soft stools with mucus and occasional blood
- Intestinal gas (excessive flatus)
- Rectal pain while having a bowel movement (tenesmus)
- Unintentional weight loss
- Abdominal tenderness
- Bloody stools
- Passage of liquid stools with streaks of blood
- Passage of 10 - 20 stools per day
Note: In 90% of people with amebiasis there are no symptoms.
Oral antiparasitic medication is the standard treatment for amebiasis. The choice of drug depends on the severity of the infection. Typically oral metronidaloze 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.
The outcome is usually good with treatment.
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.