Dysentery is an acute inflammation of the large intestine characterized by diarrhea with blood and mucus in stools. Its causes are bacillary, protozoal or helminthic infection. Amoebic dysentery is described onward and reference to schistosomiasis (Bilharziasis) is made onward.
The bacilli belong to the genus Shigella of which there are three main pathogenic groups, Shiga, Flexner and Sonne, the last two having numerous strains. In Britain over 95% of cases of bacillary dysentery in recent years have been caused by Shigella sonnei.