Shigellosis, also known as bacillary ysentery in its most severe manifestation, is a foodborne illness caused by infection by bacteria of the genus Shigella. It accounts for less than 10% of the reported outbreaks of foodborne illness in the USA. Shigellosis rarely occurs in animals other than humans and other primates like monkeys and chimpanzees. The causative organism is frequently found in water polluted with human feces, and is transmitted via the fecal-oral route. The usual mode of transmission is directly person-to-person hand-to-mouth, in the setting of poor hygiene among children.