About Balantidium coli infection

Key points

  • Balantidium coli is an intestinal parasite that causes the infection balantidiasis.
  • Symptoms can include diarrhea and abdominal pain.
  • You can get balantidiasis by consuming food or water contaminated with infective feces.
Balantidium coli parasitic cyst


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.

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.

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 compromised immune systems 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.

How it spreads

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.


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.


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


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