Shigella is a genus of bacteria that are a major cause of diarrheoa and dysentery – diarrhoea with blood and mucus in the stools – throughout the world. The bacteria are transmitted by ingestion of contaminated food or water, or through person-to-person contact. In the body, they can invade and destroy the cells lining the large intestine, causing mucosal ulceration and bloody diarrhoea. Apart from diarrhoea, symptoms of Shigella infection include fever, abdominal cramps, and rectal pain. Most patients recover without complications within seven days. Shigellosis can be treated with antibiotics, although some strains have developed drug resistance.