Enteric diseases in pigs from weaning to slaughter

The general aim of this thesis was to study enteric diseases in growing pigs, with special reference to diseases caused by Brachyspira hyodysenteriae and Lawsonia intracellularis. The occurrence of enteric diseases in “growers” is a problem of increasing importance in Sweden and an understanding of the mechanisms by which the microorganisms causes enteric diseases is essential to develop good prophylactic measures. The most important microorganisms involved in enteric diseases in grower pigs were identified as Lawsonia intracellularis and Brachyspira pilosicoli, as determined by necropsy, microbiological and histopathological examinations performed on representative growing pigs from good and poor performing herds. Diagnostic methods based on polymerase chain reaction for L. intracellularis in tissue or faecal samples were established and the results related to those obtained by necropsy and serology. An internal control, a mimic, was constructed to demonstrate inhibition of the PCR reactions and to evaluate different preparation methods. The methods for the demonstration of L. intracellularis in tissue samples were sensitive and specific, and the bacteria were reliably identified in faeces from pigs with overt disease. A number of factors interacting in the clinical expression of swine dysentery were evaluated. In this work, group-housing of pigs and the addition of 50% soybean meal in feed was shown to predispose for infection. A model was developed that enabled the sequential monitoring of disease in single animals by repeated endoscopy and biopsy sampling through a caecal cannula. This reduced the number of experimental animals required and increased the accuracy of the study. The general condition of the animal was not affected. The model was used to study the development of experimentally induced swine dysentery and the sequential development of lesions was characterised by histopathology and immunohistochemistry. An increase in the acute phase proteins serum amyloid A and haptoglobin and in monocytes was seen when haemorrhagic dysentery occurred

On the Infectious Causes of Neonatal Piglet Diarrhoea-A Review

Simple Summary This review is a summary of the current knowledge of the aetiology of neonatal porcine diarrhoea, including the early reports and the growing knowledge on the disease, some clinical features, a brief description of the suspected or known causes, pathogenesis and pathology, surveys made on the disease, and aspects of the methodology to be used in such microbiological surveys. Considerations of treatment and prophylaxis are beyond the scope of this paper. The aim of this paper is to review current knowledge on the relationship between presumptive infectious agents and neonatal porcine diarrhoea (NPD). The literature provides information on the rationale for this causation, including the first mention, main understandings gained with respect to, e.g., pathogenesis, and the knowledge to date on the specific relationships. Further, surveys on the presence and relative importance of these pathogens in NPD are included and the methodology used to identify the causation are discussed

Comparison of Multiple-Locus Variable-Number Tandem Repeat Analysis Profiles of Enteropathogenic Yersinia spp. Obtained from Humans, Domestic Pigs, Wild Boars, Rodents, Pork and Dog Food

The enteropathogenic Yersinia genus is commonly detected in wildlife including wild boars. Difficulties in its cultivation may hamper subsequent epidemiological studies and outbreak investigations. Multiple-locus variable-number tandem repeat analysis (MLVA) of Yersinia (Y.) enterocolitica and Y. pseudotuberculosis has proven useful in source attribution and epidemiological studies but has hitherto relied on the analysis of isolates. In the present study, MLVA profiles generated from 254 isolates of Y. enterocolitica indicated similarities between human, pig and rodent isolates. Further, MLVA analyses of 13 Y. pseudotuberculosis pure-cultured isolates were compared to MLVA analyses performed directly on the 14 PCR-positive enrichment broths from which the isolates originated, which showed matching MLVA profiles. This indicates that MLVA analysis performed directly on enrichment broths could be a useful method for molecular epidemiological investigations. In addition, 10 out of 32 samples of wild boar minced meat obtained from private hunters and from approved wild-game-handling establishments were PCR-positive for the presence of Y. enterocolitica and may indicate a risk for public health

Detection of atypical porcine pestivirus in Swedish piglets with congenital tremor type A-II

Background Congenital tremor (CT) type A-II is a neurological disorder characterized by tremor of the head and body of newborn piglets. The suggested causative agent of the disease is the recently found atypical porcine pestivirus (APPV). The virus has been detected in piglets suffering from congenital tremor in central Europe, South and North America and in China but no studies has so far been performed in the Nordic countries. The overarching goal of this study was to investigate if APPV is present in the brain tissue of Swedish piglets suffering from congenital tremor. From June 2017 - June 2018, 15 piglets from four Swedish farms with ongoing outbreaks of congenital tremor and 13 piglets with splay leg originating from four different farms, were investigated for presence of APPV RNA in brain tissue. Matched healthy control piglets (n=8) were also investigated. Two APPV-specific RT-qPCR methods targeting the NS3 and NS5B region, respectively, were used. A retrospective study was performed on material from Swedish piglets with congenital tremor sampled in 2004 (n=11) and 2011/2012 (n=3) using the described APPV-specific RT-qPCR methods. The total number of piglets with signs of CT in this study was 29. Results Atypical porcine pestivirus-RNA was detected in 93% (27/29) of the piglets suffering from congenital tremor. All piglets with congenital tremor from 2004 (n=11) and 2012 (n=3) were PCR-positive with respect to APPV, whereas, all of the healthy controls (n=11) were negative. The piglets with congenital tremor sampled 2017-2018 had an odds ratio of 91.8 (95% CI 3.9128 to 2153.7842, z=2.807, P=0.0050) to test positive for APPV by qRT-PCR compared to the healthy piglets (Fishers exact test p<0.0001). These findings make it interesting to continue investigating APPV in the Swedish pig-population.ConclusionThis is the first description of atypical porcine pestivirus in piglets suffering from congenital tremor type A-II in Sweden and the Nordic countries. The virus has been present in the Swedish pig population since at least 2004

Flotation—A New Method to Circumvent PCR Inhibitors in the Diagnosis of Lawsonia intracellularis

The obligate intracellular bacterium Lawsonia intracellularis causes enteritis and poor growth in weaned pigs. Cultivation is difficult and diagnosis ante mortem is mainly based on techniques such as polymerase chain reaction. However, false negative results caused by the presence of PCR-inhibitory factors constitute a problem. This study aimed to develop and evaluate a new technique, flotation, to separate L. intracellularis from inhibitors in faeces prior to PCR. The technique was evaluated by comparison to two previously evaluated and commonly used methods, preparation by boiling lysate combined with nested PCR and preparation by a commercial kit combined with conventional PCR. Continuous density centrifugation of faecal samples containing L. intracellularis suggested the buoyant density of the microbe to be between 1.064 and 1.077 g/mL. Several flotation setups were tested to achieve optimal separation of the microbe from inhibitors and faecal particles. The finally selected setup floated whole L. intracellularis from the application site at the bottom to the upper part of the gradient while inhibitory components mainly remained in the bottom. PCR was performed directly on material recovered from the upper interphase. The method was evaluated on 116 clinical samples. As compared to sample preparation by boiling combined with nested PCR, fewer samples were inhibited but also fewer positives were identified. In comparison to preparation by a commercial kit combined with conventional PCR, presently used for routine diagnosis, similar results were obtained. However, the new method was comparably faster to perform. The new method, based on flotation of Lawsonia intracellularis combined with conventional PCR, was well suited for routine diagnosis

On the carbohydrate metabolic response to an experimental infection with Brachyspira hyodysenteriae (swine dysentery) in pigs

The carbohydrate metabolic response to experimentally induced swine dysentery was studied in crossbreed pigs. Twelve pigs, with a mean weight of ~20 kg, were orally inoculated with Brachyspira hyodysenteriae strain B204. After an incubation period of 6-20 days, five animals developed swine dysentery with haemorrhagic diarrhoea and two animals developed non-haemorrhagic diarrhoea. Five animals remained healthy throughout the study. Blood samples from the animals with clinical signs of disease were collected before inoculation, several times during the course of the dysentery and finally after recovery. Blood samples from animals that remained healthy were obtained before inoculation and at slaughter four weeks later. Glucose, lactate and cortisol concentrations did not differ between sampling occasions in the healthy animals. In the sick animals, higher concentrations were observed when haemorrhagic diarrhoea occurred (mean peak value ± SD: glucose 7.6 ± 0.7 mmol/L; lactate 4.5 ± 1.7 mmol/L; cortisol 278 ± 86 nmol/L) compared to before inoculation (mean value ± SD: glucose 5.1 ± 1.2 mmol/L; lactate 1.3 ± 0.5 mmol/L; cortisol 24 ± 11 nmol/L). At slaughter, tissue samples from m. biceps femoris, m. longissimus dorsi, myocardium and liver were collected from 10 pigs and glycogen analysis was performed. Glycogen concentrations did not differ between the healthy pigs and those that developed swine dysentery: concentrations were highest in the liver and lowest in the heart. In conclusion, experimental infection with B. hyodysenteriae results in alteration of the carbohydrate metabolism, which is characterised by a transient increase in blood glucose and lactate concentrations during the initial phase of the haemorrhagic period of the disease

The occurrence of Chlamydia spp. in pigs with and without clinical disease

<p>Abstract</p> <p>Background</p> <p>Within the genera <it>Chlamydia</it>, the development of refined diagnostic techniques has allowed the identification of four species that are capable of infecting pigs. The epidemiology, clinical, and zoonotic impacts of these species are however largely unknown. The study aimed to investigate the presence of <it>Chlamydia </it>spp. in the intestines of growing pigs and in conjunctival swabs from finisher pigs, and relate the findings to clinical signs.</p> <p>Results</p> <p>By histology, 20 of 48 pigs had intestinal lesions that may be consistent with chlamydial infection. By PCR, forty-six of the pigs were positive whereas two samples were inhibited. Sequencing of 19 DNA extracts identified these as <it>Chlamydia suis</it>. By immunohistochemistry, 32 of 44 samples were positive and a significant relationship was detected between macroscopically visible intestinal lesions and a high degree of infection. By real-time PCR, a significant difference was detected between pigs with and without conjunctivitis when a Ct value of 36 was employed but not when a Ct value of 38 was employed.</p> <p>Conclusions</p> <p><it>Chlamydia suis </it>was demonstrated in most samples and overall, no correlation to clinical signs was detected. However, a correlation was noted between samples with a high degree of infection and the presence of clinical signs. It is possible, that the intensive pig production systems studied might predispose for the transmission and maintenance of the infection thus increasing the infectious load and the risk for disease in the pig.</p