Bacillary dysentery, or shigellosis, is an acute bacterial infection of the large intestine with worldwide distribution. It is common in areas of poor living conditions with low sanitary standards and low levels of personal hygiene. Travellers to countries with unsanitary restaurants are also at risk of becoming infected. During the period of illness and for several days following recovery, causative organisms - various bacteria, the most common being Shigella - are excreted in the stools and may be transmitted to other persons. Infection is a result of the oral intake of the causative organism and most often occurs directly by close person-to-person contact involving contaminated hands or indirectly by contaminated food or inanimate objects. Shigellosis rarely occurs in animals. Flies may serve as vectors.
Shigellosis is a leading cause of diarrhoeal outbreaks in the United States as well as other parts of the world. Dysentery increased in the UK in 1991; 9935 cases were reported.