title: Porcine proliferative enteropathy in Estonian pig herds: histopathology and detection of Lawsonia intracellularis by PCR.
abstract: Lawsonia intracellularis is the causative agent of proliferative enteritis in pigs (PPE). This bacterium is difficult to culture from clinical samples and antemortem demonstration is therefore usually performed by PCR on faecal samples. The aim of this study was to elucidate the frequency of L. intracellularis infection in pig herds in Estonia using PCR, histopathological methods and electronmicroscopical studies. The frequency of demonstration of L. intracellularis was highest in 9-12 weeks old pigs (68.1%). It was more frequent in growing pigs with enteritis on small farms where the system of "all-in all-out" was not practiced and where standards of hygiene were poor. Gross and histopathological studies demonstrated that characteristic macroscopic changes associated with PPE were localised to the distal jejunum and ileum.Thickened longitudinal and circumferential folds occurred in the mucosa of the affected regions of the bowel. Samples from pigs aged 4 to 20 weeks exhibited the most intensive inflammatory changes. The distal part of the jejunum, ileum and the upper third of proximal colon and cecum wall were visibly thickened with reduced luminal diameter. Hyperplasia of lymphoid tissue and, in many cases, pseudomembranous or fibrinous inflammation was found. L. intracellularis was detected in 56 young pigs using histopathological methods. Additionally, in 8 of these pigs intracellular bacteria were demonstrated in ilial epithelial cells by transmission electronmicroscopical (TEM) investigation. On the basis of these TEM investigations it was concluded that L. intracellularis causes disturbances of normal growth, differentiation and apoptosis of the epithelial cells of ileum.
authors.affiliation: Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, Department of Morphology. tonu.jarveots@emu.ee
authors.forename: Tönu
authors.initials: T
authors.lastname: Järveots
authors.forename: Tiiu
authors.initials: T
authors.lastname: Saar
authors.forename: Elbi
authors.initials: E
authors.lastname: Lepp
authors.forename: Toivo
authors.initials: T
authors.lastname: Suuroja
authors.forename: Raivo
authors.initials: R
authors.lastname: Lindjärv
authors.forename: Heiko
authors.initials: H
authors.lastname: Nathues
authors.forename: Silva
authors.initials: S
authors.lastname: Sütt
authors.forename: Diivi
authors.initials: D
authors.lastname: Põdersoo
mesh_terms: D000818:Animals; D045824:Desulfovibrionaceae Infections / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D004957:Estonia / Q000453:epidemiology; D005260:Female; D007077:Ileal Diseases / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D007082:Ileum / Q000382:microbiology / Q000473:pathology* / Q000648:ultrastructure; D007422:Intestines / Q000473:pathology; D020639:Lawsonia Bacteria / Q000235:genetics / Q000302:isolation & purification*; D008297:Male; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology