A genus of protozoa with cilia which includes Balantidium coli (B. coli). B. coli could be the biggest protozoan as well as the only ciliate parasite to infect people. The illness that B. coli causes is known as balantidiasis. Medical functions, when current, consist of persistent diarrhea, periodically dysentery, abdominal discomfort, and weight-loss. Symptoms may be extreme in debilitated persons.