Porcine proliferative enteropathy in Estonian pig herds: histopathology and detection of Lawsonia intracellularis by PCR.

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.

Phylogenetic analysis of porcine circovirus type 2 (PCV2) pre- and post-epizootic postweaning multisystemic wasting syndrome (PMWS).

The porcine circovirus type 2 (PCV2) genome encodes three major open reading frames (ORFs) encoding the replicase proteins (ORF1), the viral capsid protein (ORF2), and a protein with suggested apoptotic activity (ORF3). Previous phylogenetic analyses of complete genome sequences of PCV2 from GenBank have demonstrated 95-100% intra-group nucleotide sequence identity. However, although these isolates were readily grouped into clusters and clades, there was no correlation between the occurrence of specific PCV2 genotypes and the geographic origin or health status of the pig. In the present study, a unique dataset from a field study spanning the years pre and post the recognition of postweaning multisystemic wasting syndrome (PMWS) in Sweden was utilized. Using this dataset it was possible to discriminate three Swedish genogroups (SG1-3) of PCV2, of which SG1 was recovered from a pig on a healthy farm ten years before the first diagnosis of PMWS in Sweden. The SG1 PCV2/ORF2 gene sequence has been demonstrated to exhibit a high genetic stability over time and has subsequently only been demonstrated in samples from pigs on nondiseased farms. In contrast, SG2 was almost exclusively found on farms that had only recently broken down with PMWS whereas the SG3 genogroup predominated in pigs from PMWS-affected farms. These results further support the results obtained from earlier in vitro and in vivo experimental models and suggest the association of specific PCV2 genogroups with diseased and nondiseased pigs in the field.