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Public Health - Seattle & King County


What is it?

Amebiasis is an intestinal infection caused by a parasite, Entamoeba histolytica. The parasite produces cysts (eggs) which are passed from the body in the stool (bowel movements).


  • Fever
  • Chills
  • Diarrhea (sometimes bloody or with mucus), usually with cramps
  • Some people may have only mild abdominal discomfort or no symptoms at all
  • The symptoms start 2-4 weeks or even months after infection with a cyst.
Potential complications

In rare cases the parasite may invade the liver, lung, brain, or perforate the colon causing death.

How is it spread?

  • The parasite is spread from one person to another directly or via contaminated objects or food or water if an infected person does not wash his or her hands well after going to the bathroom. When others touch the objects or eat contaminated food they get the cysts on their hands and into their mouths. When they swallow the cysts they get the infection.
  • People are infectious as long as the cysts are shed in the stool.
Diagnosis and treatment
  • Diagnosis is done by examining a stool sample under a microscope for the presence of the parasite or its cysts.
  • People who have amebiasis are usually treated with prescription medication. There are no over-the-counter medications that will cure this infection.
  • Practicing good handwashing habits after going to the bathroom, before preparing meals and before eating.
  • Good handwashing after changing diapers.
  • Children who attend day care centers should be kept at home if they have diarrhea. If household members or other contacts develop symptoms, they should be tested for amebiasis also.
  • Foodhandlers who are infected should not work until after the treatment is finished.
Additional notes
  • People who travel to areas of the world which do not have a sanitary water supply are at greater risk for getting amebiasis.
  • Men who have sex with men are also at greater risk of getting amebiasis through sexual contact.
Report all King County cases to Public Health by calling 206-296-4774.

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