Shigella is a genus of bacteria that is Gram negative, facultatively anaerobic, non–spore-forming, nonmotile, rod shaped, and is genetically nested within Escherichia. The genus is named after Kiyoshi Shiga, who discovered it in 1897. Shigella causes disease in primates, but not in other mammals; it is the causative agent of human shigellosis. It is only naturally found in humans and gorillas. During infection, it typically causes dysentery. Shigella is a leading cause of bacterial diarrhea worldwide, with 80–165 million annual cases (estimated) and 74,000 to 600,000 deaths. It is one of the top four pathogens that cause moderate-to-severe diarrhea in African and South Asian children. Source: Wikipedia (en)