Amebiasis is caused by the parasite Entamoeba histolytica. This infection occurs worldwide. This infection is much more common among residents in and travelers to less developed countries with poor sanitation (not very clean). Amebiasis is the second most common cause of diarrhea in returning travelers.


Infection is acquired by the fecal-oral route. It can happen by:

  • Putting anything into your mouth that has been contaminated with the stool (feces) of a person who is infected.

  • Eating or drinking fecally unclean (contaminated) food or water.

  • Touching and bringing to your mouth eggs (cysts) picked up from contaminated surfaces.

  • Sexual practices that lead to oral-fecal contact.


Only about 1 in 10 people who are infected with E. histolytica become sick from the infection. Infected people can cause infection in others if they contaminate food, water, or surfaces by practicing poor hygiene.

Most people who do develop symptoms have loose stools (diarrhea) with or without stomach (abdominal) pain or cramping, or painful bowel movements. Among people who are ill, severe symptoms include:

  • Blood and mucus in their diarrheal stool.

  • Pain when squeezing the abdomen.

This severe form of amebiasis is called amebic dysentery, or amebic colitis.

Rarely, infection may spread to other organs. When spread to the liver, it can cause a hole or pocket filled with pus (abscess). Even less often, it spreads to other parts of the body, such as the lungs or brain.


Your caregiver will ask you to submit stool samples. E. histolytica is not always found in every stool sample, so you may be asked to give several samples over several different days. Diagnosis by examining the stool for the parasite can be difficult. Other parasites and cells can look very similar to E. histolytica under a microscope. Sometimes people are told that they are infected with E. histolytica even though they are not. Other tests on stool or blood (PCR, antigen, and serologic tests) may be done to confirm the diagnosis of amebiasis.


Consult with your caregiver, or an infectious disease specialist, to ensure proper diagnosis and treatment. Several medicines are available for treatment of this disease.


  • No vaccine is available.

  • Avoid sexual practices that may lead to fecal-oral transmission.

  • Travelers to less developed countries with poor sanitation should:

  • Follow precautions for food and water safety, based on the area of travel.

  • Not drink fountain drinks or any drinks with ice cubes.

  • Drink only bottled or boiled (for 1 minute) water. Or, drink bubbly (carbonated) drinks in cans or bottles.

  • Make water that is not bottled or boiled safe, by filtering it through an "absolute 1 micron or less" filter. Then, dissolve iodine tablets in the filtered water. "Absolute 1 micron" filters can be found in camping and outdoor supply stores.

  • Not eat fresh fruit or vegetables that you did not peel yourself.

  • Not eat or drink items that may not have been pasteurized, such as milk, cheese, and other dairy products.

  • Not eat or drink anything sold by street vendors.

The risk of spreading infection to others is low if the infected person is treated with antibiotics and practices good personal hygiene. This includes thorough hand washing with soap and water:

  • After using the toilet.

  • After changing diapers.

  • Before handling food.