Subclinical ileitis produced by sequential dilutions of <I>Lawsonia intracellularis</I> in a mucosal homogenate challenge model

Introduction Porcine proliferative enteropathies (PPE, also known as ileitis) are a group of enteric diseases of swine characterized by hyperplasia of crypt enterocytes in the ileum and large intestine.1,2 The causative agent is Lawsonia intracellularis (LI), a Gram-negative obligate intracellular bacterium.1,2 The disease is widespread in pigs raised under various management systems and causes significant economic impact worldwide. 1,3,4,5 The acute form occurs principally in young adults 4-12 months of age and is characterized by hemorrhage into the distal ileum resulting in bloody diarrhea or sudden death.1 The chronic form occurs mainly in pigs between 6 and 20 weeks of age and is characterized by thickening of the distal ileum often accompanied by mucosal necrosis. Affected pigs may develop diarrhea and have decreased and variable rate of gain.1,2