Lawsonia intracellularis: Proliferative Enteropathy (PDF)

LAWSONIA INTRACELLULARIS Proliferative enteropathy Aetiology and Epidemiology Lawsonia intracellularis is a gram negative, obligate intracellular, curved bacteria. Enterocytes and macrophages Pigs (horses, other animals) Economically significant. Transmission: faeco-oral, survive in fa...

LAWSONIA INTRACELLULARIS Proliferative enteropathy Aetiology and Epidemiology Lawsonia intracellularis is a gram negative, obligate intracellular, curved bacteria. Enterocytes and macrophages Pigs (horses, other animals) Economically significant. Transmission: faeco-oral, survive in faeces. Endemic Carriers Pathogenesis Invade and multiply - enterocytes and macrophages - small and large intestine Prevents maturation of enterocytes and stimulates proliferation. Infected immature epithelial cells of the intestinal crypts proliferate – hyperplastic, adenoma-like mucosa. Bacteria are shed in faeces. Clinical signs Syndromes: – Porcine intestinal adenomatosis – chronic, young growing pigs – Proliferative haemorrhagic enteropathy – young adult pigs – Necrotic ileitis – less common – end stage – Subclinical proliferative enteropathy - carriers Pigs from 6 to 20 weeks old (most common) Anorexia, Diarrhoea (haemorrhagic or not) Stunted growth – a.r.o protein loss, reduced absorption. Sudden death Pathology Macroscopic:  Dilated and turgid (swollen) intestines with corrugated folding.  No ulceration or erosions.  Diarrhoea with or without haemorrhage.  Necrotic membranes Microscopic  Hyperplasia of crypt enterocytes.  Mucosal intestinal crypts - elongated, enlarged, branched and lined by hypertrophic epithelial cells.  Curved bacteria are visible in the apical cytoplasm of the enterocytes Diagnosis Histology – silver staining, immunohistochemistry or IFA (gold standard) IFA – faecal smears PCR – ileal scrapings and faeces Serology – ELISA (screening) Control Vaccination (Enterisol IIleitis vaccine) – Timing of vaccination – 3 weeks before field infection takes place to allow pigs to build up a protective immunity. The onset of infection is most often at 8 weeks. – Serological profiling a herd at different times during growth and fattening - seroprevalence of ileitis – determines age of vaccination. Prevention - introduction of carriers Summary Lawsonia intracellularis Proliferative enteropathy (PE) – pigs, horses Small and large intestine Endemic Carriers Vaccine END