Dysentery is bloody diarrhoea, i.e. any diarrhoeal episode in which the loose or watery stools contain visible red blood. It can be caused by a number of infectious agents ranging from viruses and bacteria to protozoa and parasitic worms; it may also result from chemical irritation of the intestines.
Dysentery can be fatal as it can cause severe dehydration. Proper management of cases and of the environment, including safe water and sanitation is essential in affected areas.