A highly contagious intestinal disease caused by rod-shaped bacteria of the genus Shigella. Bacillary dysentery is a significant infection of children in the developing world, where it is transmitted by the fecal-oral route. The global disease burden is estimated as 165 million episodes and 1.3 million deaths annually. Common-source outbreaks occasionally occur in developed countries, usually as a result of contaminated food. The most common species isolated in developed countries is S. sonnei, while S. flexneri serotypes predominate in endemic areas. Epidemics of S. dysenteriae 1 occur in equatorial regions, and these outbreaks can involve adults as well as children.