Rectal dysentery is an acute intestinal infection and is the most dangerous of all diarrheal diseases. The most common cause is Shigella gram-negative dysentery bacillus (50%), but it can also be caused by other bacteria or parasites. Mild disease may resolve spontaneously to very severe with severe intoxication, convulsions, hyperthermia, cerebral edema, and rapid death without sepsis or significant dehydration.