Subclinical ileitis: Diagnostic monitoring, R2, and economics

摘要

Ileitis (Lawsonia intracellularis, LI ov PPE) is considered the most common grow-finish enteric disease in North America. Of the 3 forms of this disease: PHE (Porcine Hemorrhagic Enteropathy), PIA (Porcine Intestinal Adenomatosis) and Subclinical ileitis, the latter is considered by far the most ubiquitous and economically important. A primary challenge for today's swine practitioner is to continually monitor their clients' ileitis control programs (vaccines and/or antibiotics) with anti-mortem diagnostics (fecal PCR and IPMA serology) to determine if subclinical ileitis is present and if it is of economical significance. It can be difficult to interpret Lawsonia intracellularis PCR diagnostics due to confounding vaccine shedding with field infection shedding. It can also be difficult ro differentiate vaccine immune response vs. field infection LI titers. However, due to more advanced quantitative Fecal PCR assays with ct values and recent advances in serological IPMA (immunoperoxidase monolayer assay) antibody assays with titers, one can better interprete ante-mortem diagnostics to diagnose both clinical and subclinical ileitis to help evaluate ileitis control programs. Proper interpretation begins with an understanding of the control program inplace and an understanding of how ileitis progresses through a population of pigs.