Balantidium: A genus of protozoa parasitic in the digestive tract of vertebrate or invertebrate hosts. Asexual multiplication is accomplished by transverse binary fission. Its organisms are ovoidal in shape and have a ciliated covering over the entire body.Balantidiasis: Infection by parasites of the genus BALANTIDIUM. The presence of Balantidium in the LARGE INTESTINE leads to DIARRHEA; DYSENTERY; and occasionally ULCER.Dysentery: Acute inflammation of the intestine associated with infectious DIARRHEA of various etiologies, generally acquired by eating contaminated food containing TOXINS, BIOLOGICAL derived from BACTERIA or other microorganisms. Dysentery is characterized initially by watery FECES then by bloody mucoid stools. It is often associated with ABDOMINAL PAIN; FEVER; and DEHYDRATION.Dysentery, Bacillary: DYSENTERY caused by gram-negative rod-shaped enteric bacteria (ENTEROBACTERIACEAE), most often by the genus SHIGELLA. Shigella dysentery, Shigellosis, is classified into subgroups according to syndrome severity and the infectious species. Group A: SHIGELLA DYSENTERIAE (severest); Group B: SHIGELLA FLEXNERI; Group C: SHIGELLA BOYDII; and Group D: SHIGELLA SONNEI (mildest).