Campylobacter jejuni is a species of bacterium commonly found in animal feces. It is curved, helical-shaped, non-spore forming, Gram-negative, and microaerophilic. This species of pathogenic bacteria is one of the most common causes of human gastroenteritis in the world. Food poisoning caused by Campylobacter species can be severely debilitating, but is rarely life-threatening. It has been linked with subsequent development of Guillain–Barré syndrome (GBS), which usually develops two to three weeks after the initial illness.