“…Before 1950 Yersinia pseudotuberculosis (YP) Was known in human medicine only as a rare cause of septicaemia, but has since been shown to be the causative agent in many cases of mesenteric lYmphadenitis and erythema nodosum and responsible for less clearly defined bowel and joint symptoms (2,3,11,13,16,17,24,26,27). Yersinia enterocolitica (YE) may also cause all these clinical syndromes, but has been especially incriminated in mild abdominal upsets best described as terminal ileitis (5,30,33,38,39).…”