High Seroprevalence of Lawsonia intracellularis in Thoroughbred Farms in Southern Brazil

The aim of the present study was to carry out a serological survey to identify the seroprevalence of Lawsonia intracellularis in six Thoroughbred farms in the Southern region of the state of Rio Grande do Sul, Brazil. During 2019 and 2020, blood samples from 686 Thoroughbred horses were obtained from six different breeding farms. Horses were divided into groups according to age: (1) broodmares (>5 years), (2) two-year-old foals, (3) yearlings, and (4) 0-6 months-old foals. Blood samples were collected by venipuncture of the external jugular vein. The detection of antibodies (IgG) against L. intracellularis was performed by Immunoperoxidase Monolayer Assay. The detection of specific antibodies (IgG) against L. intracellularis in the evaluated population was 51%. The highest detection (86.8%) of IgG was in the broodmares category, while the lowest (5.2%) was in foals of 0-6 months of age. Regarding the farms, the Farm 1 had the highest (67.4%) prevalence of seropositivity against L. intracellularis, while Farm 4 had the lowest (30.6%). There was no record of clinical manifestation of Equine Proliferative Enteropathy in the sampled animals. The results of this study show the high seroprevalence of L. intracellularis in Thoroughbred farms in the Southern of Rio Grande do Sul, suggesting a large and continuous exposure to the agent.

Isolation and In Vitro cultivation of Lawsonia intracellularis from China

Lawsonia intracellularis is an obligate intracellular bacterium that cannot be cultured by conventional bacteriological methods. Pigs infected with L. intracellularis suffer from decreased daily weight gain and poor feed conversion ratio. China is a large producer of pigs, but epidemiological investigation data of L. intracellularis has not been obtained in recent years. Additionally, there is no information about a L. intracellularis strain being successfully isolated and established in cell culture in China, and the above shortcomings limit understanding of the pathogenesis of L. intracellularis and alternative prevention and control methods. The aims of this study were to estimate the seroprevalence of L. intracellularis antibodies in eight major pig-producing provinces in China during 2019-2020, to isolate L. intracellularis from infected intestines and then to establish an infection model of L. intracellularis in mice. Our results showed that of the 3586 serum samples, 2837 (79.1%, 95% CI: 77.7%, 80.4%) were seropositive for the L. intracellularis antibody. Subsequently, the L. intracellularis strain LJS19051 from China was successfully isolated and established in cell culture. Furthermore, L. intracellularis DNA and antibodies could be detected in the feces and serum samples of infected mice, respectively. Moreover, infected crypts showed typical proliferative enteropathies (PE) lesions and L. intracellularis antigen was detected in infected mice by immunofluorescence at 28 days post inoculation. The results indicated that the new L. intracellularis strain LJS19051 was obtained and could successfully proliferate in ICR mice.

Evaluation of host and bacterial gene modulation during Lawsonia intracellularis infection in immunocompetent C57BL/6 mouse model

BACKGROUND

Proliferative enteritis caused by Lawsonia intracellularis undermines the economic stability of the swine industry worldwide. The development of cost-effective animal models to study the pathophysiology of the disease will help develop strategies to counter this bacterium.

OBJECTIVES

This study focused on establishing a model of gastrointestinal (GI) infection of L. intracellularis in C57BL/6 mice to evaluate the disease progression and lesions of proliferative enteropathy (PE) in murine GI tissue.

METHODS

We assessed the murine mucosal and cell-mediated immune responses generated in response to inoculation with L. intracellularis.

RESULTS

The mice developed characteristic lesions of the disease and shed L. intracellularis in the feces following oral inoculation with 5 × l07 bacteria. An increase in L. intracellularis 16s rRNA and groEL copies in the intestine of infected mice indicated intestinal dissemination of the bacteria. The C57BL/6 mice appeared capable of modulating humoral and cell-mediated immune responses to L. intracellularis infection. Notably, the expression of genes for the vitamin B12 receptor and for secreted and membrane-bound mucins were downregulated in L. intracellularis -infected mice. Furthermore, L. intracellularis colonization of the mouse intestine was confirmed by the immunohistochemistry and western blot analyses.

CONCLUSIONS

This is the first study demonstrating the contributions of bacterial chaperonin and host nutrient genes to PE using an immunocompetent mouse model. This mouse infection model may serve as a platform from which to study L. intracellularis infection and develop potential vaccination and therapeutic strategies to treat PE.

Salmonella delivered Lawsonia intracellularis novel epitope-fusion vaccines enhance immunogenicity and confers protection against Lawsonia intracellularis in mice

Attenuated Salmonella-mediated vaccine constructs were designed by employing selected discontinuous immunodominant epitopes of LatA, FliC, and PAL antigens of Lawsonia intracellularis to create vaccines against porcine proliferative enteropathy (PPE). Whole protein sequences were subjected to in silico prediction of dominant epitopes, the stability of fusions, and hydropathicity and to ensure that the fused epitopes were feasible for expression in a Salmonella system. Two fusion constructs, one comprising LatA epitopes and the other FliC-PAL-FliC epitopes, were built into a prokaryotic constitutive expression system and transformed into the auxotrophic Salmonella host strain JOL1800. Epitope selection eliminated the majority of less immunodominant regions of target proteins and resulted in an efficient secretion platform that induced significant protective responses. Overall, our results demonstrated that the Salmonella-mediated LI- multi-epitope vaccines elicited significant humoral and cellular immune responses. Additionally, the challenge study suggested that the vaccinated mice were protected against experimental Lawsonia intracellularis infection. Based on the outcomes of the study, Salmonella-mediated LI- multi-epitope vaccines have the potential to prevent PPE.

PREVALENCE OF LAWSONIA INTRACELLULARIS INFECTION IN NONHUMAN PRIMATES AND PEST RODENTS IN A ZOOLOGICAL COLLECTION

In 2016 and 2017, Lawsonia intracellularis was isolated from several pileated gibbons (Hylobates pileatus) presenting with diarrhea in Mulhouse Zoo (eastern France). To this day, infection with this bacterium has rarely been described in nonhuman primates (NHP) in captivity or in the wild and there are no data about the prevalence or transmission of the disease. This study focuses on finding the prevalence of this infection amongst Mulhouse Zoo's NHP collection and trying to identify a source of contamination responsible for this epizooty. Forty-eight real-time PCR were conducted on feces from all NHP species in the zoo and on small mammals trapped in the NHP housing structures. No NHP was experiencing symptoms at the time of the study, however test results showed that Lawsonia intracellularis can be found in 61.76% (21/34) of the group total (n = 34) and the prevalence even increases to 92.3% (12/13) in the Lemuriform infraorder (n = 13). In small mammals (n = 14), prevalence of the bacterium is 57.17% (8/14) including 77.78% in rodents (7/9). The results of this study show that several NHP species are healthy carriers and some species of small mammals can be considered as a potential source of contamination. Because of the difficulty encountered trying to isolate the bacterium, it is plausible that infections caused by Lawsonia intracellularis have been underdiagnosed to this day, and that it could be an emerging disease in Europe. Therefore, using real-time PCR to search for this bacterium seems essential in case of diarrhea occurring in nonhuman primates. Moreover, even though further studies on contamination sources need to be conducted, the issue of the presence of rodents in NHP housing structures has to be taken very seriously and tackled with the utmost care.

Survival of Lawsonia intracellularis in porcine peripheral blood monocyte-derived macrophages

Lawsonia intracellularis, an obligately intracellular enteric bacterium, infects intestinal epithelial cells, but may also be found within macrophages in the intestinal lamina propria of affected pigs. Macrophages play an important role in host defense against infectious agents, but the role of this cell in L. intracellularis infection is not well understood. The aim of this study was to evaluate the permissibility of macrophages to L. intracellularis infection in vitro. Pure culture of L. intracellularis was added to swine peripheral blood monocyte-derived macrophages. Viability of intracytoplasmic L. intracellularis was evaluated at different time points by transmission electron microscopy (TEM). Potential replication of L. intracellularis in macrophages was also evaluated by qPCR. By TEM, phagocytosis L. intracellularis within of phagolysosomes were observed 1-hour post-infection (hpi) and bacterial structures in binary fission at 48 hpi. The number of intracellular bacteria was determined at 1, 4, 24, 48, and 72 hpi by qPCR in infected macrophages and compared to the number of intracellular bacteria from culture in McCoy cells. In both cell lines, the amount of L. intracellularis was decreased at 4 hpiand increased at 24 hpi. The number of intracellular bacteria continued to increase in McCoy cells over time. This is the first study showing interaction, survival and propagation of L. intracellularis in macrophages. These findings are critical to establish an experimental model for future studies of the pathogenesis of porcine proliferative enteropathy and the potential persistence of L. intracellularis in macrophages during chronic infections.

Mycoplasma hyopneumoniae-Lawsonia intracellularis dual challenge modulates intestinal integrity and function1

Lawsonia intracellularis (LI) and Mycoplasma hyopneumoniae (Mh) are 2 globally distributed pathogens that cause significant morbidity and mortality in grow-finish pigs. However, mechanisms that reduce growth and feed efficiency during LI and Mh infection are poorly defined. We hypothesized that reductions in performance are partially due to declines in intestinal function and integrity; thus, this study aimed to evaluate intestinal function and integrity of pigs during a 21-d Mh and LI dual challenge (MhLI). Littermate pairs of barrows (48.1 ± 6.7 kg BW) were selected; 1 pig from each pair was assigned to either MhLI challenge or nonchallenge treatments (n = 12). Pigs were individually housed, fed a corn-soybean diet, and allowed to acclimate for 21 d prior to inoculation. On days postinoculation (dpi) 0, MhLI pigs were dual inoculated with LI and Mh. On dpi 21, all pigs were euthanized for ileal and colon tissue collection. Formalin-fixed tissues were clinically scored and morphology analyzed, frozen tissues assayed for digestive enzyme activities, and fresh tissues mounted into modified Ussing Chambers to assess active nutrient transport, barrier integrity, and bacterial translocation. Data were analyzed using the Mixed Procedure of SAS with treatment as a fixed effect, age and start BW as covariates, and litter as a random effect. Compared with controls, MhLI pigs had decreased ADG (38%, P < 0.001), ADFI (25%, P < 0.001), and G:F (19%, P = 0.012). The MhLI dual challenge did not alter ileum morphology or transepithelial resistance (P > 0.10); however, ex vivo mucosal to serosal translocation of S. Typhimurium in the colon was increased (60%, P = 0.003) in MhLI pigs compared with controls. Additionally, MhLI pigs had increased ileal glucose transport (30%, P = 0.05) and decreased sucrase activity (30%, P = 0.049) compared with controls. This MhLI challenge antagonized intestinal function and integrity, and this may be a contributing factor to reduced pig performance.

Impact of Mycoplasma hyopneumoniae and Lawsonia intracellularis on the performance of pigs divergently selected for feed efficiency

Feed efficiency (FE) is a valuable trait, yet how genetic selection for enhanced FE affects other processes such as response to disease is unknown. Disease from endemic respiratory and enteric pathogens such as Mycoplasma hyopneumoniae (Mh) and Lawsonia intracellularis (LI) are common in swine production. Therefore, the aim of this study was to examine if pigs selected for high vs. low FE based on residual feed intake (RFI) respond differently to a dual respiratory and enteric challenge. Pigs selected for low RFI (LRFI, high FE) are considered more FE compared to their high RFI (HRFI, low FE) selected counterparts. Using a 2 × 2 factorial design, 25 littermate pairs from the HRFI and 25 littermate pairs from the LRFI line (barrows, 50 ± 7 kg BW) were selected, with one pig from each pair assigned to individual pens in either the challenge or the nonchallenge (control) rooms (n = 25 barrows/line/challenge). On days post inoculation (dpi) 0, the challenged pigs were inoculated with LI and Mh (MhLI). Feed intake, BW, fecal swabs, and serum samples were collected and recorded weekly for 42 d. On dpi -2 and 47, 14 littermate pairs (n = 7 barrows/line/challenge) were utilized for initial and final body composition scans using dual-energy X-ray absorptiometry to calculate longitudinal whole body tissue accretion rates for lean, protein, fat, and bone mineral content. Serum antibody levels and fecal shedding of LI were used to confirm infection. Control pigs remained negative by all measures during the 6-wk trial and MhLI inoculated pigs were confirmed positive via serological antibody responses by dpi 14 for LI and Mh. There were no interactions between RFI line and challenge status for any overall performance parameter (P > 0.05). The 6-wk MhLI challenge resulted in a 17% reduction in ADG, a 12% reduction in ADFI, and a 7% reduction in G:F vs. Controls (P < 0.05). In addition, compared to the Control pigs, MhLI challenge reduced lean, protein, and lipid accretion rates by 16% (P < 0.05). Genetic selection for high FE resulted in decreased ADFI and increased G:F (P < 0.01), but did not impact ADG or tissue accretion vs. low FE pigs. Collectively, these results demonstrate that a dual enteric and respiratory pathogen challenge reduced ADG, ADFI, G:F, and tissue accretion in growing pigs. Further, there was no evidence that selection for enhanced FE based on RFI index affects response to disease.

Vaccination Against Lawsonia intracellularis Decreases Shedding of Salmonella enterica serovar Typhimurium in Co-Infected Pigs and Alters the Gut Microbiome

Salmonella enterica serovar Typhimurium continues to be a major cause of foodborne illness worldwide and pork can serve as a source of infection. Co-infection of S. enterica with Lawsonia intracellularis, a common intestinal pathogen of swine, has been found as risk factor for increased S. enterica shedding. The objective of this study was to investigate if vaccination against L. intracellularis could lead to decreased S. Typhimurium shedding. To test this hypothesis, pigs were challenged with either S. Typhimurium or S. Typhimurium and L. intracellularis, with and without L. intracellularis vaccination (n = 9 per group). A non-challenged group served as a negative control. Vaccination decreased the shedding of S. Typhimurium in co-infected animals by 2.12 log10 organisms per gram of feces at 7 days post infection. Analysis of the microbiome showed that vaccination led to changes in the abundance of Clostridium species, including Clostridium butyricum, in addition to other compositional changes that may explain the protection mediated against S. Typhimurium. These results indicate that vaccination against L. intracellularis in co-infected herds may provide a new tool to increase food safety by helping to prevent S. enterica without the need for antibiotics.

Lawsonia intracellularis and Porcine Circovirus type-2 infection in Estonia

The present study describes the reasons of post-weaning distress in Estonian pig herds. Here we examined the natural cases of Lawsonia intracellularis and porcine circovirus 2 (PCV2) infection and co-infections. The presence of L. intracellularis in swine herds were tested by PCR and by histopathological methods, whereas PCV2 was detected by real-time-PCR and immunohistochemical stainings. Seven of the 11 investigated herds with signs of post-weaning wasting were infected with L. intracellularis and all 11 herds with PCV2. From the analysed samples 22.2% were infected with L. intracellularis and 25% with PCV2. The results of microbiological studies suggested that the piglets suffered from enteritis and pneumonia. Escherichia coli and Pasteurella multocida often aggravated the process of illness. The frequency of L. intracellularis was high in pigs 7-12 weeks old (18.5-42.7%) and PCV2 infection was too high in pigs 7-12 weeks old (24.8-32.7%). E. coli was often a co-factor with L. intracellularis and PCV2. The primary reasons of post weaning wasting were PCV2 and E. coli, later aggravated by L. intracellularis and other pathogens. Our results indicated that different pathogens have an important role in developing post-weaning wasting. Proliferative intestinal inflammation caused by L. intracellularis is mainly characterised by its localization and morphological findings. The main gross lesions were the enlargement of mesenteric lymph nodes and thickening of the wall of ileum. In post-weaning multi-systemic wasting syndrome there are characteristic histological lesions in lymphoid tissues. They consist of a variable degree of lymphocyte depletion, together with histiocytic and/or multinucleate giant cell infiltration. This basic lymphoid lesions is observable in almost all tissues of a single severely affected animal, including lymph nodes, Peyer's patches and spleen. Sporadically, multifocal coagulative necrosis may be observed.

Seroprevalence of Lawsonia intracellularis antibodies in intensive pig farms in China

BACKGROUND

Porcine proliferative enteropathy caused by Lawsonia intracellularis (L. intracellularis) is a major concern to the pig industry worldwide. Although 8.3 billion pigs are produced each year in China, few reports on the prevalence of L.intracellularis infection are available. The aim of the current study was to estimate the seroprevalence of L. intracellularis antibodies in intensive pig farms in China.

RESULTS

A total of 1060 serum samples were collected from 14 commercial pig farms located throughout China. Animals from all age groups were sampled including pre-weaning piglets, weaners, fattening pigs, adult sows and boars. Antibodies against L. intracellularis were detected using a specific blocking ELISA. Of the 1060 serum samples, 602 were identified as positive using the ELISA test. The apparent seroprevalence of L. intracellularis seropositivity was 57% (95% CI 50 to 64%). The true prevalence (that is, prevalence corrected for the imperfect sensitivity and specificity of the testing method) was 77% (95% CI 70 to 83%).

CONCLUSIONS

The highest true prevalence was observed in sows and boars, suggesting that within a herd these stock classes are a reservoir for infection. The prevalence of L. intracellularis seropositivity in local breed pigs was significantly less than that in imported breeds. A higher seroprevalence was found in pigs in herds in Central and Northern China, which may correspond to the greater use of the intensive production systems in these areas. We conclude that L. intracellularis is widely prevalent in commercial pigs in China.

Species-specificity of equine and porcine Lawsonia intracellularis isolates in laboratory animals

Lawsonia intracellularis infection causes proliferative enteropathy (PE) in many mammalian species, with porcine and equine proliferative enteropathy (PPE and EPE) known worldwide. Hamsters are a well-published animal model for PPE infection studies in pigs. There is no laboratory animal model for EPE infection studies and it is not known whether there is species-specificity for equine or porcine isolates of L. intracellularis in animal models. The objective of this study was to determine whether it is possible to generate typical EPE lesions in hamsters after inoculation with an equine strain of L. intracellularis (EPE strain) and whether it is comparatively possible to generate PPE lesions in rabbits after inoculation with a porcine strain of L. intracellularis (PPE strain). In 2 separate trials, 4-week-old and 3-week-old weanling golden Syrian hamsters were challenged with EPE strains and compared to uninfected (both trials) and PPE-infected controls (Trial 2 only). Concurrently, 6 female New Zealand white juvenile rabbits were infected with PPE strain and observed concomitantly to 8 similar rabbits infected with EPE strain for a different experiment. Hamsters and rabbits were observed for 21 to 24 days post-infection (DPI), depending on the experiment. Neither infected species developed clinical signs. The presence of disease was assessed with diagnostic techniques classically used for pigs and horses: immune-peroxidase monolayer assay on sera; quantitative polymerase chain reaction (qPCR) detection of molecular DNA in feces; and hematoxylin and eosin (H&E) stain and immunohistochemistry (IHC) on intestinal tissues. Our results showed that EPE-challenged hamsters do not develop infection when compared with PPE controls (IHC, P = 0.009; qPCR, P = 0.0003). Conversely, PPE-challenged rabbits do not develop typical intestinal lesions in comparison to EPE-challenged rabbits, with serological response at 14 DPI being significantly lower (P = 0.0023). In conclusion, PPE and EPE strains appear to have different host-specificities for hamsters and rabbits, respectively.

Lawsonia intracellularis-associated ulcerative and necro-hemorrhagic enteritis in 5 weanling foals

This report describes 5 cases of fatal Lawsonia intracellularis-associated ulcerative and necro-hemorrhagic enteritis in weanling Thoroughbred and Standardbred foals. The lesions are similar to those of the L. intracellularis-associated ulcerative and necro-hemorrhagic enteritis syndrome in pigs. Two foals had concurrent severe typhlo-colitis as a result of a large burden of encysted cyathostomes. The clinical, diagnostic, and therapeutic challenges, and the potential complications encountered during the management of such cases are discussed.

The rabbit as an infection model for equine proliferative enteropathy

The objective of this study was to demonstrate the susceptibility of rabbits to Lawsonia intracellularis obtained from a case of clinical equine proliferative enteropathy (EPE). This is a preliminary step toward developing a rabbit infection model for studying pathogenesis and therapy of EPE in horses. Nine does were equally assigned to 3 groups. Animals in 2 groups (Group 1 and Group 2) were orally inoculated with different doses of cell-cultured L. intracellularis. Controls (Group 3) were sham-inoculated. Feces and blood were collected before the rabbits were infected and at 7, 14, and 21 days post-infection (DPI). Serum immunoglobulin G (IgG) titers were measured using an immunoperoxidase monolayer assay (IPMA) and fecal samples were analyzed with quantitative polymerase chain reaction (qPCR). A doe from each group was euthanized at 7, 14, and 21 DPI for collection and evaluation of intestinal samples. Tissues were stained by routine hematoxylin and eosin (H&E) method and immunohistochemistry (IHC) with L. intracellularis-specific mouse monoclonal antibody. At 14 DPI, serologic responses were detected in both infected groups, which maintained high titers through to 21 DPI. Lawsonia intracellularis DNA was detected in the feces of Group 2 on 7 DPI and in both infected groups on 14 DPI. Gross lesions were apparent in Group 1 and Group 2 on 14 DPI. Immunohistochemistry confirmed L. intracellularis antigen within cells of rabbits in Group 1 and Group 2 on 7, 14, and 21 DPI. No lesions, serologic response, shedding, or IHC labeling were found in Group 3 rabbits. This study describes an EPE rabbit model that simulates natural infection, as typical lesions, immune response, and fecal shedding were present.

Lawsonia intracellularis proliferative enteropathy in a foal

A weanling foal was diagnosed with proliferative enteropathy caused by Lawsonia intracellularis based on history, clinical findings of depression, anorexia, weight loss, colic, diarrhea, and ventral edema, and a combination of serology and fecal PCR. An epidemiological investigation on the premises revealed that many of the other foals and adult horses were seropositive for L. intracellularis, despite being clinically normal, and identified a dog as a potential carrier and source of infection for the foal. The foal was successfully treated with a combination of azithromycin and rifampin.

Proliferative enteropathy (PE)-induced changes in the calbindin-immunoreactive (CB-IR) neurons of inferior mesenteric ganglion supplying the descending colon in the pig

A subpopulation of the pig inferior mesenteric ganglia (IMG) neurons projecting to the colon exhibit calbindin-like immunoreactivity. It is not known if there are any changes in the chemical coding patterns of these neurons during porcine proliferative enteropathy (PE). To answer this question, juvenile Large White Polish pigs with clinically diagnosed Lawsonia intracellularis infection (PE; n = 3) and a group of uninfected controls (C; n = 3) were compared. The retrograde tracer fast blue (FB) was injected into the descending colons of all animals and then tissue comprising IMGs from both groups was processed for double-labeling immunofluorescence with calbindin-D28k (CB) in combination with either tyrosine hydroxylase (TH), neuropeptide Y (NPY), somatostatin (SOM), vasoactive intestinal polypeptide (VIP), nitric oxide synthase, Leu-enkephalin, substance P, vesicular acetylcholine transporter, galanin, or pituitary adenylate cyclase-activating polypeptide. Immunohistochemistry revealed changes in the chemical coding pattern of calbindin-immunoreactive neurons in the inferior mesenteric ganglia of the pig. In control animals, FB/CB-positive neurons were immunoreactive to TH, NPY, SOM, and VIP. In the experimental group, TH-expressing neurons were unaffected, NPY-expressing neurons were increased, whereas the number of neurons immunoreactive to SOM or VIP was reduced. Changes in chemical coding of CB neurons during PE may play an important role in adaptation of these IMG cells under pathological conditions.

Changes in pituitary adenylate cyclase-activating Peptide 27-like immunoreactive nervous structures in the porcine descending colon during selected pathological processes

This study reports on changes in the pituitary adenylate cyclase-activating peptide 27-like immunoreactive (PACAP-27-LI) nerve structures of the enteric nervous system (ENS) in the porcine descending colon, caused by chemically induced inflammation, nerve injury, and proliferative enteropathy (PE), which is a "natural" inflammation of the porcine digestive tract. The distribution pattern of PACAP-27-LI structures was studied using the immunofluorescence technique in the circular muscle layer, enteric plexuses (i.e., myenteric plexus (MP), outer submucous plexus (OSP), and inner submucous plexus (ISP)), and in the mucosal layer. Under physiological conditions, PACAP-27-LI perikarya have been shown to constitute 4.04 ± 0.66, 6.66 ± 0.77, and 11.19 ± 0.74 % in the MP, OSP, and ISP, respectively. Changes in PACAP-27 immunoreactivity depended on the pathological factor studied. The numbers of the PACAP-27-LI perikarya amounted to 12.26 ± 1.43, 12.28 ± 0.79, and 21.13 ± 1.19 % in chemically induced colitis, 17.83 ± 0.88, 9.03 ± 1.05, and 20.72 ± 1.35 % during PE and 10.65 ± 0.82, 6.88 ± 1.04, and 14.04 ± 1.09 % after axotomy in MP, OSP, and ISP, respectively. All of the studied processes generally resulted in an increase in the number of PACAP-27-LI nerve fibers in the circular muscle and mucosal layers. The obtained results suggest that PACAP-27-LI nerve structures of ENS may participate in various pathological states within the porcine descending colon, and their functions probably depend on the type of pathological factor.

Lawsonia intracellularis-associated proliferative enteritis in weanling foals in the Netherlands

Equine proliferative enteropathy (EPE) is an emerging infectious enteric disease caused by the obligate intracellular gram-negative bacterium Lawsonia intracellularis. EPE was tentatively diagnosed in six weanling foals, aged between 5 and 7 months. Clinical signs included depression, anorexia, ventral oedema, and weight loss. Plasma biochemistry consistently revealed severe hypoproteinaemia. The ante-mortem diagnosis of EPE was based on clinical signs, hypoproteinaemia (6/6), the detection of moderate-to-high titres of L. intracellularis antibody (6/6), and severe thickening of the small intestinal wall on ultrasonography (2/2), or L. intracellularis detected in faeces by PCR (I/2). The first foal died despite treatment and at post-mortem examination the tentative diagnosis was EPE. Three foals from the same farm, which showed similar clinical symptoms were treated with azithromycin and rifampicin; two survived. Post-mortem examination of the foal that died confirmed the tentative clinical diagnosis of EPE on the basis of the lesions found and the detection of L. intracellularis--DNA in the ileum and jejunum. The fifth foal died despite intensive treatment and the post-mortem examination revealed lymphohistiocytic enteritis, typhlitis, and widespread thrombosis in several organs. The sixth foal recovered completely after treatment. This report confirms the presence of clinical L. intracellularis infection in weanling foals in the Netherlands and shows the difficulty in reaching a definitive ante-mortem diagnosis.

A follow up study on antibodies against Lawsonia intracellularis in mares and foals from two breeding farms in Germany

Equine proliferative enteropathy (EPE) caused by Lawsonia (L.) intracellularis is an emerging disease in foals, particularly in North America. Since a case report in Germany exists, the objective of this study was to examine the incidence of L. intracellularis-antibodies in healthy horses from two German breeding farms. In group 1, serum samples from 24 (year 1) and 16 (year 2) Haflinger mares and their foals were taken. In group 2, over a period of five months, serum samples of six warmblood mares and foals were collected monthly from birth until the foals became seronegative. Serum samples were tested using an ELISA system. Results are expressed as Percentage of Inhibiton (PI). All adult mares (100%) of both groups were seropositive at each point in time (PI-value > 30). In group 1,7/24 foals (29.2%) in year 1 and 4/16 foals (25%) in year 2 had antibodies.The seropositive foals from year 2 had the same dams as the seropositive foals from year 1. In group 2 five of six foals were seropositive after birth. Antibodies decreased from March to July in mares and foals. In July, all five foals tested negative for the first time between the ages of 82 and 141 days (median 115 days). PI-values of mares were significantly correlated with PI-values of their foals. Higher PI-values were seen in younger foals and early in spring. Loss of antibodies in foals at the age of three to five months could be a risk factor for infection and appearance of EPE.

Analysis of bacterial load and prevalence of mixed infections with Lawsonia intracellularis, Brachyspira hyodysenteriae and/or Brachyspira pilosicoli in German pigs with diarrhoea

Lawsonia (L.) intracellularis, Brachyspira (B.) hyodysenteriae and B. pilosicoli are important pathogens in domestic pig production world-wide, responsible for porcine intestinal adenomatosis, swine dysentery, and porcine intestinal spirochetosis, respectively. Conventional PCR is the major diagnostic tool in the detection of the three pathogens, but the sole detection of bacterial DNA might lead to misinterpretations of results with respect to their clinical relevance, especially with mixed infections. Thus, the present study targeted the detection and quantification of the three pathogens in samples from herds with a case history of diarrhoea. Herds and samples were selected by the practitioners on a voluntary basis. Results were based on 1176 individual samples from 95 herds from Southern Germany. The pathogens were detected simultaneously by multiplex real-time PCR. The overall prevalence for L. intracellularis, B. hyodysenteriae and B. pilosicoli was 12.6%, 8.4% and 3.2% in faecal samples and 48.4%, 24.2% and 31.6% in herds, respectively. Sixty one percent, 82.6%, and 73.4% of herds positive for L. intracellularis, B. hyodysenteriae, and B. pilosicoli, respectively, had mixed infections. Median log values of DNA equivalents/g of faeces for L. intracellularis, B. hyodysenteriae and B. pilosicoli were 3.3, 5.9 and 3.2, with maxima of 8.3, 8.0 and 6.3, respectively. Within herd prevalence of B. hyodysenteriae and B. pilosicoli as well as the load of B. hyodysenteriae were significantly associated with the severity of diarrhoea.

The seroprevalence of Lawsonia intracellularis in horses in The Netherlands

Equine proliferative enteropathy caused by Lawsonia intracellularis is an emerging disease of weanling foals and affects their growth and development. The prevalence of Lawsonia intracellularis in The Netherlands is not known. The aim of the study was to investigate the seroprevalence of Lawsonia intracellularis in horses in The Netherlands. Blood samples were taken from healthy foals before and after weaning and from healthy yearlings and mature horses on farms throughout The Netherlands. These samples were analysed for the presence of Lawsonia intracellularis-specific antibodies with a blocking ELISA. White blood cell count, packed cell volume, and total protein concentration were also measured in all foals. Information regarding housing, pasture access, and contact with pig manure on the premises was obtained for all animals. The prevalence of Lawsonia intracellularis antibodies in foals increased significantly from 15% before weaning to 23% after weaning (p = 0.019); it was 89% in yearlings and 99% in horses older than 2 years. There was no significant difference in seroprevalence between the pasture-kept and stable-confined adult horses (97% and 100%, respectively), and there was no significant influence of contact with pig manure. None of the sampled animals showed clinical disease. In conclusion, the results suggest that Lawsonia intracellularis is widespread in The Netherlands and that seropositivity is not necessarily associated with clinical problems. The high seroprevalence in adult horses suggests long-term persistence of antibodies against Lawsonia intracellularis or constant exposure to the bacterium.

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.

Evidence of cell-mediated immune response and specific local mucosal immunoglobulin (Ig) A production against Lawsonia intracellularis in experimentally infected swine

The purpose of this study was to detect cell-mediated and local humoral immune responses to Lawsonia intracellularis in pigs inoculated with a pure culture of the pathogenic isolate or with an intestinal mucosa homogenate. Twenty-four 5-week-old pigs were inoculated with a pure culture of L. intracellularis (n = 10), an intestinal mucosa homogenate from proliferative enteropathy diseased pigs (n = 10), or a control solution (n = 4). All animals were bled 0, 7, 14, and 20 d post-inoculation (pi). Serum was tested for immunoglobulin (Ig) G against L. intracellularis and for the production of interferon (IFN)-gamma by peripheral blood mononuclear cells (PBMC) after inoculation with L. intracellularis total proteins. Delayed-type hypersensitivity (DTH) reactions were evaluated 24 and 48 h after intra-dermal injection of different concentrations of L. intracellularis antigen 20 d pi. All animals were euthanized on day 22, intestinal lavages of ileum and IgA titrations were done. Weak IFN-gamma production was detected in 1 pig from the pure culture group and 2 pigs from the mucosal homogenate group 14 d pi, and in 2 animals from both groups 20 d pi. All pigs, in both inoculated groups, were seropositive for IgG on day 20. Inoculated pigs from both groups showed very weak dose-dependent DTH reactions, which were more evident at 24 h than 48 h pi. Eight pigs from the pure culture group and 7 from the mucosa homogenate group had detectable IgA titers in the intestinal lavage 22 d pi. In conclusion, specific local intestinal humoral and weak cell-mediated immune responses can be detected in pigs experimentally infected with L. intracellularis.

Faecal shedding and serological cross-sectional study of Lawsonia intracellularis in horses in the state of Minas Gerais, Brazil

REASON FOR PERFORMING THE STUDY

Proliferative enteropathy, caused by the intracellular bacterium Lawsonia intracellularis, has been described in horses in Australia, the USA, Canada and European countries but has not been reported in Latin America. The prevalence of the disease in horses worldwide is unknown.

OBJECTIVE

To evaluate the presence of subclinical L. intracellularis infection in horses in the state of Minas Gerais, Brazil.

METHODS

A longitudinal study using serology and PCR for detecting antibodies (IgG) and shedding of L. intracellularis in faecal samples, respectively, was conducted using a total of 223 horses from 14 different horse farms in Minas Gerais, and from the Veterinary School of UFMG equine herds in Minas Gerais. The immunoperoxidase technique in glass slides was used as the serological test.

RESULTS

Twenty-one horse sera had immunoglobulin G titres of 1:60 and were considered positive. The PCR technique in faeces for L. intracellularis DNA identified 7 horses as faecal shedders. Horses shedding the organism appeared healthy, indicating that subclinical infection of L. intracellularis occurred in the horses.

CONCLUSION

Seropositivity and detection of faecal shedding of L. intracellularis indicates the presence of the agent in the equine population in Minas Gerais.

POTENTIAL RELEVANCE

Results of this study should alert clinicians in countries where proliferative enteropthy in horses has not been reported to consider this disease as a possible cause of enteric disease.

Diagnosis of Lawsonia intracellularis infection in pigs after vaccination or antimicrobial treatment

Diagnosis of infection with Lawsonia (L.) intracellularis, the causative agent of porcine proliferative enteropathy, is routinely based on the detection of L. intracellularis in faeces and/or tissue samples by PCR. Furthermore, infection can be determined by the detection of antibodies in serum samples. The aim of this comparative study was to examine whether results from molecular biology and serological testing are influenced by applying live bacteria vaccine Enterisol Ileitis or antimicrobial treatment to pigs naturally exposed to L. intracellularis. Decreased shedding was detected in tylosin treated pigs only. Thus, the distribution of 345 pigs into groups of 0-, 1- or > or = 2-times positive by PCR was significantly influenced by the treatment (P < 0.0001). A global effect of positive PCR results on average daily weight gain was also highly significant (P < 0.0001). The serological reaction was detected by a blocking ELISA after infection but not after vaccination independent of treatment. The results indicate no influence of vaccination on applied diagnostic tests.

Evaluation of the humoral immune response and fecal shedding in weanling foals following oral and intra-rectal administration of an avirulent live vaccine of Lawsonia intracellularis

Equine proliferative enteropathy (EPE) caused by Lawsonia intracellularis has recently been recognized as an emerging disease in foals. Whilst the clinical entity, diagnostic evaluation and treatment of affected foals have been well established and described, preventive measures for EPE have remained largely unaddressed. The objectives of this study were to investigate the humoral immune response and onset and duration of fecal shedding in foals after oral and intra-rectal administration of a modified-live vaccine of L. intracellularis. Foals were vaccinated twice, 3 weeks apart, via oral drenching after pre-medication with a proton-pump inhibitor (omeprazole; group 1), intra-rectally (group 2) or orally without any pre-medication (group 3). The health status of the foals was monitored daily, with feces and serum collected at regular intervals for Polymerase Chain Reaction (PCR) and serology. All foals remained healthy and no adverse vaccine reactions were observed. Fecal shedding lasted from 1 to 12 days and was mainly detected in foals receiving the intra-rectal vaccine 11-15 days following the first vaccine administration. Serological responses were measured in the majority of the vaccinated foals. All foals vaccinated intra-rectally seroconverted after the first vaccine, compared to 50% and 0% of foals in groups 1 and 3, respectively. Pre-medication with omeprazole prior to oral vaccination in group 1 foals led to an earlier and stronger detectable humoral response compared to non pre-medicated foals.

Enteritis and colitis in horses

Enteritis and colitis remain challenging and life-threatening diseases despite many recent advances. Successful treatment is largely dependent on early recognition and directed therapy, which is facilitated by obtaining a complete history and physical examination. A number of new therapies and methods of monitoring critically ill patients have become integral components of treatment success. The critical monitoring of equine foals and adults continues to be an exciting and emerging field.

[Literature review of the diagnosis of porcine proliferative enteropathy]

Lawsonia (L.) intracellularis is the etiologic agent of ileitis, which occurs in different forms in pigs. The infection can be demonstrated by several methods. In routine diagnosis the indirect detection of L. intracellularis is conducted by measuring antibodies performing an indirect IFT or ELISA. Furthermore, an IFT and PCR on faecal and/or tissue samples are well established for the direct detection. The suitability of PCR on faecal samples is frequently discussed. Problems are related to various inhibitors that are component of faeces. When interpreting laboratory results, the past medical history of pigs, i.e. antimicrobial treatment, has to be considered. Since 2004 a new vaccine against ileitis is licensed. A possible influence of vaccination on diagnostic testing, especially PCR and ELISA, is hardly investigated. Therefore, the interpretation of laboratory results from vaccinated animals is, considering the current literature, restrained.

An outbreak of Lawsonia intracellularis infection in a standardbred herd in Ontario

An outbreak of protein-losing enteropathy associated with Lawsonia intracelluaris infection was diagnosed in 6 standardbred foals from a farm in Ontario. Wildlife exposure may have been involved in the perpetuation of disease in this outbreak. The clinical presentation, treatment, outcomes, and pathological findings are described.

In situ hybridization for Lawsonia intracellularis--specific 16s rRNA sequence in paraffin-embedded tissue using a digoxigenin-labeled oligonucleotide probe

An in situ hybridization (ISH) procedure with a digoxigenin-labeled oligonucleotide probe for detection of Lawsonia intracellularis in paraffin-embedded tissue is described. This technique recognized 71% of PCR-positive cases and was thus superior to Warthin-Starry silver stain, which only detected 41%. The presented ISH is of comparable sensitivity to previously published immunohistochemical assays and is recommended for laboratories wishing to diagnose L. intracellularis infections in tissue sections but without access to antibodies.

Seroprevalence of Lawsonia intracellularis in different swine populations in 3 provinces in Canada

Porcine proliferative enteropathy caused by Lawsonia intracellularis is an important enteric disease in swine throughout the world. Information regarding the distribution of this pathogen in Canadian swine herds would be beneficial for the creation of control protocols. Pigs from Ontario, Quebec, and Alberta were tested by using an indirect immunofluorescence assay for antibodies to L. intracellularis. Pig seroprevalence was calculated as the proportion of pigs positive from total pigs tested in the targeted population. Seroprevalence (+/- standard error [s(x)]) in market hogs in Ontario from farrow-finish (FF) farms and finishing (FIN) farms were significantly different at 77% (s(x) = 7%) and 29% (s(x) = 15%), respectively. Seroprevalence for sows and gilts in FF and farrowing and nursery (FAR + NUR) farms in Ontario were 90% (s(x) = 3%) and 93% (s(x) = 6%), respectively. Seroprevalence in breeding females in Quebec from FF and FAR farms was 82% (s(x) = 5%) and 87% (s(x) = 3%), respectively. Seroprevalence (57%, s(x) = 8%) in finishing pigs in Alberta from FF farms was significantly different from that of multisite (MS) farms and FIN farms, 6% (s(x) = 6%) and 9% (s(x) = 5%), respectively. Lawsonia intracellularis appears to be widespread in Canada and the seroprevalence on FF farms is higher than that on FIN and MS farms, possibly due to the presence of breeding females or management differences.

Proliferative enteropathy: a global enteric disease of pigs caused byLawsonia intracellularis

Proliferative enteropathy (PE; ileitis) is a common intestinal disease affecting susceptible pigs raised under various management systems around the world. Major developments in the understanding of PE and its causative agent,Lawsonia intracellularis, have occurred that have led to advances in the detection of this disease and methods to control and prevent it. Diagnostic tools that have improved overall detection and early onset of PE in pigs include various serological and molecular-based assays. Histological tests such as immunohistochemistry continue to be the gold standard in confirmingLawsonia-specific lesions in pigspost mortem. Despite extreme difficulties in isolatingL. intracellularis, innovations in the cultivation and the development of pure culture challenge models, have opened doors to better characterization of the pathogenesis of PE throughin vivoandin vitro L. intracellularis–host interactions. Advancements in molecular research such as the genetic sequencing of the entireLawsoniagenome have provided ways to identify various immunogens, metabolic pathways and methods for understanding the epidemiology of this organism. The determinations of immunological responsiveness in pigs to virulent and attenuated isolates ofL. intracellularisand identification of various immunogens have led to progress in vaccine development.

Isolation of Lawsonia intracellularis in Korea and reproduction of proliferative enteropathy in pigs and hamsters

Lawsonia intracellularis (L. intracellularis) was isolated from a Korean pig suffering acute proliferative enteropathy. In vitro culture conditions of L. intracellularis were established in McCoy cells. Pigs and hamsters experimentally infected with the pure culture of L. intracellularis reproduced clinical signs and intestinal lesions of proliferative enteropathy. The presence of L. intracellularis in the intestinal lesions was confirmed by immunohistochemistry with L. intracellularis-specific monoclonal antibodies.

Re-challenge of pigs following recovery from proliferative enteropathy

An experimental challenge model was developed to demonstrate Lawsonia intracellularis colonization and reproduction of proliferative enteropathy (PE) in naïve weaner pigs. Groups of pigs were orally dosed with between 10(10) and 10(5)L. intracellularis extracted from haemorrhagic PE affected mucosa. Pigs were monitored for clinical signs and intestinal lesions of PE and evidence of bacterial colonization by serology and faecal polymerase chain reaction (PCR). One group of challenged pigs were necropsied after 21 days to confirm the reproduction of PE. L. intracellularis colonization and seroconversion was delayed in pigs dosed with lower numbers of L. intracellularis. When faecal shedding of L. intracellularis ceased to be detected in all of the challenged pigs, they were re-dosed orally with approximately 10(10)L. intracellularis and monitored for evidence of re-colonization and clinical disease. This study demonstrated that pigs previously challenged with L. intracellularis were protected from re-colonization and clinical disease on subsequent exposure 10 weeks later, regardless of the initial dose of L. intracellularis.

Health management with reduced antibiotic use - experiences of a Danish pig vet

During the late 1990s, all use of antibiotic growth promotors for production animals was gradually banned in Denmark. At the same time, the legislation on prescription of medicine was tightened and registration of usage became mandatory. Following the ban, the prevalence of diarrhoea - often caused by Lawsonia intercellularis - increased, which led to an expected increased use of therapeutic antibiotics. However, the consumption never reached the same amount of antibiotics as distributed before the ban. As a consequence, production performance dropped with a reduction of 18 g to 50 g per day in daily gain and mortality increased by an extra 0.6% to 1.5%, especially in the weaner period. The cost of this is at least from 1 to 3 US dollars per animal. No reliably substitute to antibiotic has been found yet, but improvement of the diet and management on all levels are important factors for compensation. Further investigations in this area are called for in the future.

Distinction between porcine circovirus type 2 enteritis and porcine proliferative enteropathy caused by Lawsonia intracellularis

The presence of porcine circovirus type 2 (PCV2) was studied immunohistochemically in formalin-fixed, paraffin wax-embedded samples of intestinal tissue from 80 pigs with a clinical history suggestive of Lawsonia intracellularis-associated diarrhoea. Histopathologically, enteritis of varying intensity was diagnosed in 64 of the pigs. Of these 64 animals, 34 (18%) were infected with both PCV2 and L. intracellularis. Of the remaining 30 cases of enteritis, 23 (77%) were attributed to PCV2 infection alone. The PCV2-associated enteritis cases showed necrotizing ileitis and colitis, indistinguishable macroscopically from proliferative enteritis (PE) due to L. intracellularis. Histopathologically, L. intracellularis-positive intestines showed adenomatous proliferation of crypt enterocytes, whereas PCV2 enteritis was characterized by histiocytosis of varying intensity, with PCV2-positive cells in the submucosa, lamina propria and crypt epithelium, as well as in the lymphoid tissue of the ileum and colon. Multinucleated giant cells, however, were seen in both infections. PCV2 was about three times more likely to be detected in L. intracellularis-negative than in L. intracellularis-positive samples (P<0.001). There was no association between PCV2 and other intestinal bacterial pathogens. The study demonstrated that PCV2 enteritis should be borne in mind in the differential diagnosis of L. intracellularis infection in pigs aged 2-4 months with a clinical history of diarrhoea.

First experience on the effect of in-feed lincomycin for the control of proliferative enteropathy in growing pigs

This trial's aim was to evaluate the effect of in-feed lincomycin for the control of proliferative enteropathy (PE; also known as ileitis) in growing pigs, in which it is associated with significant morbidity levels. Investigation regarding the efficacy of this substance in growing pigs has never been carried out before in a field trial. The trial farm had a previous history of PE outbreaks. On day 1 of the trial (age of 62 +/- 1.5 days), 240 pigs were divided into two groups of 120 pigs/group which were allocated into five pens of 24 pigs each. Therefore, a randomized block design was used with two experimental groups (T1-T2) and five replicates (pens) per group. T1 group served as negative control (NC) animals which were receiving no medication and conversely T2 group received in-feed lincomycin at the dose of 110 mg/kg of feed. The treatment period lasted for 3 weeks, followed by an observation period of 4 weeks up to the age of 111 +/- 1.5 days which was the end of the grower stage. Administration of lincomycin at a dose of 110 mg/kg of feed had beneficial effects compared with the NC group. The pigs of T2 group showed significant improvement of their production parameters in terms of average daily body gain (ADG) and feed conversion ratio (FCR) not only during the treatment period (ADG: 0.515 +/- 0.050 versus 0.481 +/- 0.071 and FCR: 2.38 +/- 0.05 versus 2.56 +/- 0.08, for T2 and T1 groups respectively), but also during the remaining period until the end of the grower stage (observation period: ADG: 0.687 +/- 0.019 versus 0.646 +/- 0.044 and FCR: 2.58 +/- 0.02 versus 2.74 +/- 0.02 respectively). Other effects in the T2 group refer to the reduction of diarrhoea prevalence (mean pen diarrhoea score during the whole grower stage: 0.200 +/- 0.060 versus 0.632 +/- 0.041 respectively), morbidity rates (morbidity rates during the whole grower stage: 15.83% versus 45.00% respectively) and the reduction of Lawsonia intracellularis prevalence as shown by polymerase chain reaction diagnostic method (at the end of the treatment period: 10.0% versus 60.0% respectively). In conclusion, treatment with 110 mg lincomycin/kg of feed for 21 consecutive days had a beneficial effect on the control of PE in growing pigs.

In vitro cultivation and partial characterization of Lawsonia intracellularis from a Japanese field case of porcine proliferative enteropathy

Lawsonia intracellularis isolated from a Japanese field case of porcine proliferative enteropathy (PPE) was cultivated and partially characterized. The bacterial cells isolated from the intestinal mucosa of a pig suffering from the acute form of PPE were used to inoculate rat small intestine cells (IEC-18) and human epithelial cells (HEp-2). Infected foci, which were stained with L. intracellularis-specific rabbit antiserum, were observed in the cell culture at 5 days post inoculation. The DNA sequence of several genes in the Japanese isolate had high similarity with those of the L. intracellularis type strain, suggesting the genetically close relationship of the two strains. This is the first report describing the cultivation and partial characterization of L. intracellularis originated in Japan.

Diagnostic and epidemiological features of Lawsonia intracellularis enteropathy in 2 foals

Two clinical cases of equine proliferative enteropathy are described. Both foals had a positive fecal polymerase chain reaction, but shedding of the bacterium stopped <4 days after therapy was initiated. One foal was serologically positive 3 days after onset of clinical signs and remained positive for more than 6 months.

Effect of including distillers dried grains with solubles in the diet, with or without antimicrobial regimen, on the ability of growing pigs to resist a Lawsonia intracellularis challenge1

A disease challenge experiment was conducted to determine if including 10% dried distillers grains with solubles (DDGS) in the diet, with or without antimicrobial supplementation, reduces the incidence or severity, or both, of intestinal lesions in growing pigs after an Lawsonia intracellularis challenge. One hundred 17-d-old weaned pigs were blocked by sex, ancestry, and BW and randomly allotted to 1 of 5 treatment groups: negative control, unchallenged, corn-soy diet; positive control, challenged, corn-soy diet; 10% DDGS diet, challenged; positive control with antimicrobial regimen, challenged; and 10% DDGS diet with antimicrobial regimen, challenged. For antimicrobial-supplemented treatments, diets contained 33 ppm bacitracin methylene disalicylate throughout the experiment, with chlortetracycline (Aureomycin) pulsed at 550 ppm from d 3 prechallenge to d 11 postchallenge. Challenged pigs were orally inoculated with 8.0 x 10(8) L. intracellularis organisms after a 4-wk prechallenge period. On d 21 postchallenge, pigs were euthanized, lesions of intestinal mucosa were evaluated, and ileal tissue samples were analyzed by immunohistochemistry to determine the presence and proliferation rate of L. intracellularis. Compared with other dietary treatments, feeding a diet containing 10% DDGS reduced ileum and colon lesion length and prevalence (P < 0.05) and reduced severity of lesions in the ileum (P < 0.05) and colon (P < 0.10) in challenged pigs. Compared with other challenged pigs, those fed the diet containing the antimicrobial regimen had a lower prevalence and severity of lesions in the jejunum (P < 0.05) and tended to have reduced total tract lesion length (P = 0.11). Compared with other challenged pigs, pigs on the 10% DDGS diet with antimicrobial regimen exhibited no differences in length, severity, or prevalence of lesions (P > 0.15), but fecal shedding of L. intracellularis was reduced on d 14 postchallenge (P < 0.05). No dietary effects on fecal shedding were observed by d 20 postchallenge (P > 0.10). The proportion of cells infected with L. intracellularis was reduced when DDGS (P = 0.05) or antimicrobial (P = 0.10) diets were fed. Under the conditions of this experiment, dietary inclusion of 10% DDGS appears to provide some benefit to growing pigs subjected to a moderate L. intracellularis challenge, similar to those of a currently approved antimicrobial regimen.

Effect of dietary inclusion of distillers dried grains with solubles, soybean hulls, or a polyclonal antibody product on the ability of growing pigs to resist a Lawsonia intracellularis challenge

An experiment was conducted to determine if dietary inclusion of distillers dried grains with solubles (DDGS), soybean hulls, or soybean hulls sprayed with an egg-based, polyclonal antibody product would reduce the incidence or severity of infection, or both, in growing pigs after a Lawsonia intracellularis challenge. One hundred 17-d-old weaned pigs were blocked by sex, ancestry, and BW, and randomly allotted to 1 of 5 treatment groups: negative control, unchallenged, corn-soy diet; positive control, challenged, corn-soy diet; 20% DDGS diet (D), challenged; 5% soybean hulls diet (SH), challenged; and SH sprayed with a polyclonal antibody product diet, challenged. Challenged pigs were orally inoculated with 6.4 x 10(8) L. intracellularis organisms after a 4-wk prechallenge feeding period. On d 21 postchallenge, pigs were euthanized, lesions of intestinal mucosa were evaluated, and ileal tissue samples were analyzed by immunohistochemistry to determine the presence and proliferation rate of L. intracellularis. Challenging pigs with L. intracellularis reduced growth rate, feed intake, and efficiency of gain (P < 0.02) and increased the proportion of internal organ weights relative to BW (P < 0.01). Dietary treatment did not affect growth performance pre- or postchallenge (P > 0.10). Heart, empty stomach, and liver weights were similar among dietary treatments (P > 0.10). Weight of the large intestine as a percentage of BW was increased in D and SH pigs compared with positive control pigs (P < 0.05). Lesion length, prevalence, and severity, and fecal shedding of L. intracellularis were primarily unaffected by dietary treatment (P > 0.10), although ileal lesion length and severity observed tended to be greater in the SH sprayed with polyclonal antibody product diet vs. the D pigs (P < 0.10). Results from a previous study indicated that diet composition may affect length, severity, and prevalence of lesions caused by L. intracellularis in growing pigs subjected to a moderate challenge. However, beneficial results were not observed by feeding the dietary treatments used in this study.

Effect of dietary inclusion of distillers dried grains with solubles on the ability of growing pigs to resist a Lawsonia intracellularis challenge1

An experiment was conducted to determine if including distillers dried grains with solubles (DDGS) in the diet of growing pigs reduces the incidence or severity of infection after a Lawsonia intracellularis challenge. Eighty 17-d-old weaned pigs were blocked by sex, ancestry, and BW and randomly allotted to 1 of 4 treatment groups: negative control (NC), unchallenged, corn-soy diet; positive control (PC), challenged, corn-soy diet; 10% DDGS diet (10D), challenged; and 20% DDGS diet (20D), challenged. Challenged pigs were orally inoculated with 1.5 x 10(9) L. intracellularis organisms after a 4-wk prechallenge feeding period. On d 21 postchallenge, pigs were euthanized, lesions of intestinal mucosa were evaluated, and ileal tissue samples were analyzed by immunohistochemistry to determine the presence and proliferation rate of L. intracellularis. Compared with unchallenged pigs, challenging pigs with L. intracellularis reduced growth rate, feed intake, and efficiency of gain (P < 0.01) and increased gauntness (P < 0.05) and diarrhea (P < 0.01). Diet did not affect growth performance postchallenge (P > 0.40). Feeding 10 or 20% DDGS diets did not reduce lesion length, prevalence, proliferation of L. intracellularis, or severity of lesions (P > 0.10). Thus, dietary inclusion of DDGS did not reduce the incidence or severity of lesions under the conditions of a severe L. intracellularis challenge used in this study.

Lawsonia intracellularis infection in the large intestines of pigs

In this study we examined the proliferative enteropathy, caused by the obligate intracellular bacterium Lawsonia intracellularis, in colon of naturally infected pigs, using immunohistochemistry, in situ hybridisation and scanning confocal laser microscopy. When 396 pigs submitted for routine laboratory examination were investigated, large intestinal gross lesions were seen in 93, including 74 cases of L. intracellularis colitis (proliferative enteropathy). Fifty-one pigs without recorded colonic gross lesions revealed L. intracellularis colitis microscopically. In four cases, L. intracellularis was only revealed in colon. Fifty-seven pigs were positive for L. intracellularis in the small intestines only. Thus, the overall prevalence of colonic infection in L. intracellularis-positive animals was as high as 69% (125 out of 182). In comparison, the large intestinal pathogens Brachyspira hyodysenteriae and Salmonella enterica were only isolated from 5 and 4 of the 93 cases, respectively. Morphologically, an unforeseen severe involvement of the subepithelial mucosa with multiple L. intracellularis found free and within large macrophages was observed in areas with acute infection. The distribution of whole L. intracellularis organisms was confirmed by in situ hybridisation and scanning confocal laser microscopy. The significance and possible role of subepithelial infection in the proliferative enteropathy is discussed. In conclusion, the study shows that L. intracellularis is a prevalent cause of naturally acquired colitis in pigs.

Detection of Lawsonia intracellularis in wild boar and fallow deer bred in one game enclosure in the Czech Republic

The prevalence of Lawsonia intracellularis between wild boar (Sus scrofa) and fallow deer (Dama dama) bred in one game reserve was investigated using the nested PCR method. In the study, 88 clinically healthy wild boars of different age categories and two fallow deer bagged in the game reserve were examined. Lawsonia intracellularis was demonstrated in the mucous membrane of the intestine of eight (9.1%) wild boars and one fallow deer. Of the nine wild boar whose tissues of corresponding lymph nodes were examined in addition to the mucous membrane of the ileum, one tested positive for the microorganism. A relationship between the occurrence of L. intracellularis and age of wild boar was demonstrated. Because wild boar and fallow deer are bred together in one game reserve, the possibility of inter-species transfer of L. intracellularis should be borne in mind.

Effects of oral vaccination against Lawsonia intracellularis on growing-finishing pig's performance in a pig production unit with endemic porcine proliferative enteropathy (PPE)

The aim of the present study was to evaluate the effect of oral vaccination against Lawsonia intracellularis (LI) on growing-finishing pig's performance. In a large Hungarian growing-finishing pig production unit, pigs with positive LI status were randomly divided into 2 groups and treated as follows: Group one: growing pigs (n = 4112) were LI vaccinated with an avirulent oral live vaccine (Enterisol Ileitis Boehringer Ingelheim Vetmedica, Inc., St. Joseph, USA). Group two: growing pigs (n = 4188 pigs) have not received LI vaccination. Culling and mortality rates, reasons for culling or mortality, and average daily weight gain were evaluated. Porcine proliferative enteropathy (PPE) caused culling and mortality rates were lower (0.2 % vs. 14.9 %, P < 0.001), and vaccinated pigs had lower none-PPE caused culling and mortality rates compared with the non-vaccinated ones (1.4 vs. 2.6 %, P > 0.05). While systemic infections and social stress or cannibalism related culling or mortality were significantly (P < 0.05) lower in vaccinated than in non-vaccinated pigs, reasons for culling or mortality due to non-LI caused diseases were non-significantly different between the vaccinated and non-vaccinated pigs. Average daily weight gain was higher (P < 0.05) in the LI vaccinated group of animals compared with the non-vaccinated ones (780 +/- 45 g vs. 660 +/- 71 g). The present results indicate that that LI vaccination does not only prevent PPE, but might result in more resistance and tolerance against other infectious and management caused losses.