An evaluation of balantidiasis begins with a medical history and physical examination.

Unless dehydration is present, the physical exam is usually normal.

Testing for balantidiasis is necessary to confirm this diagnosis. A stool specimen is required for examination, in order to look for the parasite, Balantidium coli.

A stool culture can also detect:

• Campylobacter enteritis
• Cryptosporidium enterocolitis
• Giardiasis
• Pseudomembranous colitis
• Salmonella gastroenteritis
• Shigella gastroenteritis
• Traveler's diarrhea due to bacterial infection

Additional tests used to evaluate balantidiasis may include:

• Complete blood count
• Liver profile
• Kidney profile
• A specimen for microscopic study is usually obtained during sigmoidoscopy.