Yersinia enterocolitica is a species of gram-negative coccobacillus-shaped bacterium, belonging to the family Enterobacteriaceae. The major animal reservoir for Y. enterocolitica strains that cause human illness is pigs; Infection is most often acquired by eating contaminated food, especially raw or undercooked pork products. They might also be contracted by touching an infected animal, drinking contaminated well water, or on rare occasions, from contaminated transfusions. Y. enterocolitica causes gastrointestinal disease (gastroenteritis) which may develop into mesenteric lymphadenitis with manifestations closely resembling those of acute appendicitis. Infection with Y. enterocolitica can cause a variety of symptoms depending on the age of the person infected. It occurs most often in young children. Common symptoms in children are fever, abdominal pain, and diarrhea, which is often bloody. In older children and adults, right-sided abdominal pain and fever may be the predominant symptoms. In a small proportion of cases, complications such as skin rash, joint pains, or spread of bacteria to the bloodstream can occur. A RISE in serum titre of Yersinia-specific IgA antibodies indicates current infection.