Balantidium coli Infection FAQs


What is Balantidium coli?

Balantidium coli is an intestinal protozoan parasite that causes the infection called balantidiasis. While this type of infection is uncommon in the United States, humans and other mammals can become infected with Balantidium coli by ingesting infective cysts from food and water that is contaminated by feces. Mostly asymptomatic, Balantidium infection can cause such symptoms as diarrhea and abdominal pain.

Where is Balantidium coli endemic?

Balantidium coli infection in humans is rare in the United States. Balantidium coli is found throughout the world, but it is most prevalent in tropical and subtropical regions and developing countries. Because pigs are an animal reservoir, human infections occur more frequently in areas where pigs are raised, especially if good hygiene is not practiced.

How is Balantidium coli transmitted?

Balantidium coli is transmitted through the fecal-oral route. Humans can become infected by eating and drinking contaminated food and water that has come into contact with infective animal or human fecal matter. Infection can occur in several ways, including the following examples:

  • eating meat, fruits, and vegetables that have been contaminated by an infected person or contaminated by fecal matter from an infected animal,
  • drinking and washing food with contaminated water, or
  • having poor hygiene habits.

What are the signs and symptoms?

Most people infected with Balantidium coli experience no symptoms. Balantidium coli infects the large intestine in humans and produces infective microscopic cysts that are passed in the feces, potentially leading to re-infection or infection of others. People who are immune-compromised are the most likely to experience more severe signs and symptoms. These include persistent diarrhea, dysentery, abdominal pain, weight loss, nausea, and vomiting. If left untreated, perforation of the colon can occur.

Is there a test for Balantidium coli infection?

Yes. Stool samples can be examined by a laboratory. Microscopic examination can detect Balantidium coli in the stool.

Is this contagious?

Yes. Balantidium coli is contagious by the fecal-oral route.

Is there treatment?

Yes. The three medications often used to treat Balantidium coli are tetracycline, metronidazole, and iodoquinol. See your health care provider for treatment.

How can I prevent Balantidium coli?

Balantidium coli infection can be prevented when traveling by following good hygiene practices. Wash your hands with soap and warm water after using the toilet, changing diapers, and before handling food. Teach children the importance of washing hands to prevent infection. Wash all fruits and vegetables with clean water when preparing or eating them, even if they have a removable skin.

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This information is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the parasites described above or think that you may have a parasitic infection, consult a health care provider.

Page last reviewed: September 16, 2020