Symptoms and Signs of Amebiasis (Entamoeba Histolytica Infection)

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Medically Reviewed on 9/17/2021

Doctor's Notes on Amebiasis (Entamoeba Histolytica Infection)

Amebiasis is a disease caused by a one-celled parasite called Entamoeba histolytica. Infection can be found in any setting where sanitation is poor, and it is most commonly found in people in the tropics. Men who have sex with men are also at increased risk for amebiasis. E. histolytica infection can be treated successfully with antibiotics. Good sanitation practices can help prevent amebiasis. 

Only about 10% to 20% of people who are infected with E. histolytica become sick, usually within 2 to 4 weeks of infection. Symptoms of amebiasis are often mild and may include

Symptoms of a severe form of amebiasis called amebic dysentery include

  • stomach pain,
  • bloody stools, and 
  • fever.

In rare cases E. histolytica invades the liver and forms an abscess. Also rarely, the infection may spread to other parts of the body, such as the lungs or brain.

What Is the Treatment for Amebiasis?

Infections that do not produce symptoms are typically not medically treated unless they are found in non-endemic geographic areas.

  • Medications are available to treat patients who have documented presence of E. histolytica cysts in the stool where there is no invasion into the tissues (known as intestinal amebiasis).
  • The antibiotic metronidazole is recommended to treat cases of invasive amebiasis.  
  • Tinidazole (Tindamax) is FDA approved for treatment of both intestinal or extraintestinal (invasive) amebiasis.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.