Yersinia enterocolitica infection causes the disease yersiniosis, which is a zoonotic disease occurring in humans as well as a wide array of animals such as cattle, deer, pigs, and birds. Many of these animals recover from the disease and become asymptomatic carriers. Yersinia enterocolitica is a species of gram-negative coccobacillus-shaped bacterium, belonging to the family Enterobacteriaceae. Only a few strains of Y. enterocolitica cause illness in humans. The major animal reservoir for Y. enterocolitica strains that cause human illness is pigs, but other strains are also found in many other animals. Acute Y. enterocolitica infections produce severe diarrhea in humans, along with Peyer"s patch necrosis, chronic lymphadenopathy, and hepatic or splenic abscesses. Additional symptoms may include entero-colitis, fever, mesenteric adenitis, erythema nodosum and acute terminal ileitis, which may be confused with appendicitis or Crohn"s disease.