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.     

Distribution of Brachyspira hyodysenteriae and Lawsonia intracellularis in healthy and diarrhoeic pigs

Although Brachyspira (B.) hyodysenteriae and Lawsonia (L.) intracellularis are widely distributed in pigs in Germany, there exists limited information on their clinical relevance.To get more insight into their potential role in swine diarrhoeal disease, in 2002 and 2003 faecal specimens from healthy pigs (n=1445) as well as from diarrhoeic pigs (n=2002) were tested by polymerase chain reaction (PCR) for the presence of both agents. Of the specimens from healthy pigs L. intracellularis and B. hyodysenteriae were detected in 7.3% and 6.7%, respectively. In contrast, of the diarrhoeic pigs the ratios of positive samples amounted to 19.4% for L. intracellularis and 17.9% for B. hyodysenteriae. Concerning the age of the diseased animals, in growing pigs the detection rates of L. intracellularis and B. hyodysenteriae were nearly identical (16.4% and 14.2%, respectively). In fattening pigs a significant higher number of animals were affected with B. hyodysenteriae (35.8%) than with L. intracellularis (28.2%). On the other hand, in sows L. intracellularis (35.6% positive samples) was dominant compared to B. hyodysenteriae (21.2% positive samples). Considering the nearly threefold higher percentage rates of L. intracellularis and B. hyodysenteriae in diarrhoeic pigs in comparison to healthy pigs, it is concluded that both agents play an important role in swine diarrhoeal disease. The results further indicated that in fattening pigs B. hyodysenteriae and in sows L. intracellularis have a dominant role, respectively.     

Longitudinal study of Salmonella species in 90 Alberta swine finishing farms

The aim of this study was to determine the farm prevalence of Salmonella in 90 Alberta finishing swine farms over a 5-month period, to evaluate Salmonella distribution in the farm environment and to describe Salmonella serovar diversity on these farms. Ten veterinary practitioners selected 90 Alberta swine farms based on an annual production of > or =2000 market pigs per farm and the willingness of the producers to participate in the study. Between May and September 2000, twenty samples were collected from finishing swine and the environment of each farm. The annual production of selected farms represented approximately 25% of the market swine production in Alberta. Participating farms were geographically representative of major swine production areas in Alberta. Sixty (66.7%) farms had at least one Salmonella-positive sample, with confidence interval (CI) of 57.1-77.2%. Salmonella were detected in 14.3% of fecal and 20.1% of environmental samples. The number of Salmonella-positive samples per farm ranged from 1 to 19. Among environmental samples, Salmonella were most frequently recovered from boots (38.6%) and the main drain (31.8%). Twenty-two serovars were detected on the 60 Salmonella-positive farms. Serovars Typhimurium (78 isolates), Derby (71 isolates) and Infantis (47 isolates) were the most common. A single serovar was detected on 58 farms, while 2, 3 and >3 serovars were detected on 15, 10 and 7 farms, respectively. The Salmonella farm status changed frequently over the 5-month period indicating the dynamic nature of Salmonella infections on these farms.     

Immunohistochemical detection of Lawsonia intracellularis in tissue sections from pigs

The aim of the present study was to develop an immunohistochemical method (IHC) for detection of Lawsonia intracellularis (L. intracellularis) in formalin-fixed, paraffin embedded sections of intestines from pigs and to implement this method in differential diagnosis of swine diseases with diarrhea in postweaning pigs. The study was conducted on 165 sections of intestines (ileum, caecum and colon) collected from 76 pigs, representing 42 Polish pig farms. The animals included in the analysis suffered from diarrhea, with bloody or grey to brown feces, and were suspected of porcine proliferative enteropathy (PPE). Sections of intestines were analyzed for the presence of L. intracellularis by polymerase chain reaction (PCR) and IHC. Among 165 intestinal samples from pigs with diarrhea, L. intracellularis DNA was detected by PCR in 33 (20.0%) samples. In this group, 30 samples (18.2% of all the samples tested) were also found positive in IHC, while only 3 (1.8%) were IHC-negative. One hundred thirty-two (80.0%) samples were negative in both tests. The PCR- and IHC-positive samples originated from 11 pigs, 4- to 20-week old, from 8 farms. L. intracellularis antigen was visualized by IHC mostly in intestinal crypts and/or in mononuclear cells of the lamina propria). The positive signal in epithelial cells was observed close to the luminal borders, creating typical specifically stained rims around the crypt lumina. The results of the present study further confirm the usefulness of IHC in the detection of L. intracellularis antigen in the intestinal tissues.     

Seroprevalence of Lawsonia intracellularis in large pig production units

In 11 'farrow-to-finish' outdoor or indoor production units, blood samples from late pregnant gilts were tested by indirect immunofluorescence antibody (IFA) serum assay for Lawsonia intracellularis. The offspring of positively tested gilts were tested at 2, 7, 12, 17, 22 and 27 weeks of age for seroprevalence of Lawsonia intracellularis. All offspring of IFA positive gilts were seronegative at 2 and 7 weeks of age. At 12 weeks of age 81.0% of indoor and 51.0% of outdoor pigs were tested positive. While at 17 weeks of age 82.5% of indoor-raised pigs showed seropositivity, in outdoor units the seropositivity declined to 31.3%. At weeks 22 and 27 indoor-raised pigs still showed marked seropositivity (17.7% and 11.5%) but their outdoor-raised counterparts revealed declining values (7.4% and 0%).     

Seroprevalence of antibodies against Lawsonia intracellularis among growing pigs raised in indoor versus outdoor units

OBJECTIVE: To determine change over time in sero-prevalence of antibodies against Lawsonia intracellularis among growing-finishing pigs housed in indoor versus outdoor facilities. DESIGN: Serologic survey. ANIMALS: 93 pigs born to seropositive gilts and raised in indoor (n = 49) or outdoor (44) growing-finishing facilities. PROCEDURE: Blood samples were collected from the pigs 2, 6, 10, 14, 18, 22, and 26 weeks after birth and tested for antibodies against L intracellularis with an indirect immunofluorescence assay. RESULTS: None of the pigs were seropositive 2 or 6 weeks after birth.Ten weeks after birth, 74% and 76% of pigs in indoor and outdoor growing-finishing facilities were seropositive, respectively, whereas 14 weeks after birth, the percentage of pigs in indoor growing-finishing facilities that were seropositive was substantially higher than the percentage of pigs in outdoor facilities that were. From 18 weeks after birth to the end of the study, none of the pigs in outdoor growing-finishing facilities were seropositive, whereas low percentages of pigs in indoor facilities were seropositive 18, 22, and 26 weeks after birth. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that seroprevalence of antibodies against L intracellularis decreases faster among growing-finishing pigs housed in outdoor facilities than among growing-finishing pigs housed in indoor facilities.     

Colonisation and shedding of Lawsonia intracellularis in experimentally inoculated rodents and in wild rodents on pig farms

Lawsonia intracellularis is an intracellular bacterium causing proliferative enteropathy in various animal species, and is considered an economically important pathogen of pigs. Rats and mice have been implicated as external vectors for a wide range of pig pathogens, including L. intracellularis. Previous studies have demonstrated L. intracellularis infection and proliferative enteropathy in rodents, but did not show the duration of shedding or the number of L. intracellularis shed by infected rodents, and therefore the infection risk that rodents pose to pigs. In this study, the number of L. intracellularis shed in the faeces and intestinal mucosa of wild rats trapped on pig farms was determined by a quantitative real time polymerase chain reaction assay. The prevalence of L. intracellularis in wild rats trapped on pig farms with endemic proliferative enteropathy (PE) was very high (≥ 70.6%), and large numbers of L. intracellularis were shed (10(10)/g of faeces) in a small proportion of wild rats. The duration of colonisation in laboratory rats and mice challenged with porcine isolates of L. intracellularis was also shown. Faecal shedding of L. intracellularis persisted for 14-21 days in rats and mice that were mildly affected with histological lesions of PE. The humoral immune response to L. intracellularis persisted for 40 days in both species. This study demonstrates that rodents may be an important reservoir of L. intracellularis on piggeries, and hence rodent control is important in disease eradication programs on pig farms.     

Occurrence of Lawsonia Intracellularis and Brachyspira spp. infection in swine suffering from diarrhoea

Principal aim of this study was to examine fecal samples from pigs suffering from diarrhea for the presence of Lawsonia intracellularis, Brachyspira hyodysenteriae and Brachyspira pilosicoli. The molecular techniques such as PCR and nested PCR were employed to detect the presence of p78 fragment of genomic DNA specific for Lawsonia intracellularis as well as fragment of tlyA gene specific for Brachyspira hyodysenteriae and 16S rDNA gene of Brachyspira pilosicoli. We assumed that about 25% of pigs were infected with Lawsonia intracellularis, about 10% with Brachyspira hyodysenteriae and only 0,8% with Brachyspira pilosicoli. In about 3% mixed infection with L. intracellularis and B. hyodysenteriae was observed. Results were comparable in herds that differed in quantity, breeding technology, hygienic standards and preventive treatment with different chemotherapeutics.     

Therapeutic efficacy of water-soluble lincomycin-spectinomycin powder against porcine proliferation enteropathy in a European field study

Controlled clinical trials to a standardised protocol were conducted into the effect of a water-soluble antibiotic on proliferative enteropathy and its causative agent (Lawsonia intracellularis) on commercial pig farms at six sites in four European countries. Clinical signs of the disease and L intracellularis-specific polymerase chain reaction (PCR)-positive pigs were detected in pens of six- to 12-week-old pigs (weighing 5 to 55 kg) immediately before each trial. Matched pens of randomised pigs were either left unmedicated (32 to 59 pigs per trial), or medicated orally with 10 mg/kg of a water-soluble combination of lincomycin and spectinomycin powder (21 and 42 mg, respectively, of antibiotic activity per litre) for either seven days (33 to 61 pigs per trial), or 14 days (33 to 61 pigs per trial), delivered via the drinking water. Investigators did not know which pens received which treatment In most of the affected pigs in each trial, diarrhoea due to L intracellularis resolved within three to seven days after the medication began, whereas most unmedicated pigs remained diarrhoeic for at least 10 days. On average the medicated pigs gained more weight than the unmedicated pigs over the 21-day trial period (P=0.01). In two trials, the absence of L intracellularis after the treatment ended was confirmed by the PCR.     

Prevalence of pseudorabies virus infection and associated infections in six large swine herds in Illinois.

Sera were collected from 6 large farrow-to-finish swine herds infected with pseudorabies virus (PRV) in Illinois. All herds were participating in the Large Herd Cleanup Study, a USDA-initiated project to evaluate the feasibility of eradicating pseudorabies from large farms (greater than 400 sows) by use of a combination of vaccination and management changes. Herd size ranged between 425 and 1,500 breeding females. Between April and July 1990, sera for measurement of PRV antibodies were obtained from 113 to 156 sows and 112 to 162 finishing pigs (body weight greater than 70 kg)/herd. Duplicate sera from 30 sows and 30 market-weight pigs/herd were obtained for measurement of serum antibodies to the following associated organisms: swine influenza virus, transmissible gastroenteritis virus, encephalomyocarditis virus, Actinobacillus pleuropneumoniae, Eperythrozoon suis, and 6 serovars of Leptospira interrogans. Prevalence of PRV antibodies attributable to field virus infection ranged between 53.8 and 100% for sows and between 0.7 and 97.3% for finishing pigs, as determined by the appropriate differential test for the vaccine being used on each farm. In only 1 herd, PRV seroprevalence was increased with higher sow parity. For associated infections, the risk of seropositivity attributable to PRV was not significant (for most infections) on all farms and varied among farms. Thus, pseudorabies did not appear, in general, to increase susceptibility to infection with other disease agents.     

A Lawsonia intracellularis transmission study using a pure culture inoculated seeder-pig sentinel model

Transmission of Lawsonia intracellularis from experimentally inoculated pigs to naive swine was demonstrated in this study. The study was conducted using conventional pigs divided into three groups as follows: principles inoculated with L. intracellularis, sentinels, and controls. The pigs were inoculated and paired on 13 and 9 days post-inoculation with a sentinel pig for 7 days. Fecal samples and serum samples were collected throughout the study for polymerase chain reaction (PCR) and antibody testing by indirect fluorescent antibody techniques. After co-mingling, the inoculated group was necropsied; sentinel and control pigs were necropsied 7-14 days later. The intestinal tracts were evaluated grossly and microscopically for lesions. PCR was performed on intestinal mucosal scrapings and feces. Warthin-Starry and fluorescent antibody staining procedures were conducted to confirm colonization with L. intracellularis. Gross and microscopic lesions typical of porcine proliferative enteropathy (PPE) were observed in both the inoculated and sentinel groups. Transmission was demonstrated from inoculated principle pigs to sentinel pigs. PCR results detected cyclical shedding of L. intracellularis in the feces. Seroconversion occurred in pigs that were exposed to L. intracellularis. From this study, it was demonstrated that transmission of L. intracellularis can occur easily in an environment with experimentally infected pigs and that PCR can be a useful tool to monitor fecal shedding of the organism.     

Toxoplasma gondii infection in slaughter pigs in Serbia: seroprevalence and demonstration of parasites in blood

ABSTRACT: A seroepizootiological study of Toxoplasma gondii infection involving a total of 488 slaughter pigs (468 market-weight pigs and 20 sows) in the Belgrade area, also included examination of the presence of T. gondii in the blood. Blood sampled at the slaughter line was examined for specific antibodies by modified direct agglutination, and blood clots of those seropositive at titres of 1:50-1:12800 were bioassayed in mice. The overall seroprevalence was 9.2%, significantly higher (p = 0.0063) in sows (30.0%) than in market-weight pigs (8.3%). Amongst the 22 bioassays performed, a total of 16 (72.7%) were positive, by observation of T. gondii cysts (12), seropositivity (7, including 3 in which cysts were not detected), and/or detection of T. gondii DNA by real-time PCR (12, including one otherwise negative). The positive bioassays originated from the blood of 12 market-weight pigs and 4 sows. Despite a general increase in the rate of demonstration of T. gondii with the increase in the specific antibody level, the association was not significant (p = 0.101). The risk of infection was 41-fold increased in sows vs market-weight pigs, and 15-fold in pigs from smallholders' finishing type farms vs those from large farrow-to-finish farms. The presence of viable T. gondii in a proportion of the samples indicates that some of the pigs had an active parasitaemia at the time of slaughter, which, along with the seroprevalence established, points to a potential source of human infection in Serbia. This is the first report on parasitaemia in naturally infected swine.     

Patterns of exposure to Lawsonia intracellularis infection on European pig farms

A serological investigation was made of the patterns of exposure of pigs to Lawsonia intracellularis, the causative agent of proliferative enteropathy (ileitis), on farms in France and Spain. Blood samples from groups of adult female pigs in breeding programmes and from postweaning pigs were monitored, the latter every month for five months, by a L. intracellularis-specific immunofluorescence seroassay. Four of 33 farms monitored in France (12 per cent) and three of 29 farms monitored in Spain (10.3 per cent) remained free of clinical signs and seronegative throughout the study. The postweaning pigs on all of the remaining French farms and on 20 of the 26 remaining Spanish farms had a pattern of infection characterised by seroconversion in the grower period, generally between eight and 16 weeks of age. The seroprevalence in these groups ranged from 8 to 20 per cent. On all of these farms at least 15 per cent of the breeding females tested were seropositive, and the farms were under similar management systems, with a continuous flow of pigs or between buildings on one site, so-called 'one site, farrow-to-finish'. On the six remaining Spanish farms, under two management groups, a multiple-site system was used, with the piglets being separated from the adults at weaning and moved to a separate location. On three of these farms, the pattern of infection was characterised by seroconversion later in the finisher period, at between 16 and 20 weeks of age, and none of the breeding females was seropositive. On the three other multiple-site farms the pattern of infection resembled that on the one-site farms. On all of the farms, the seroconversion of groups of pigs was frequently associated with clinical or subclinical signs of ileitis.     

Factors associated with circulation of pseudorabies virus within swine herds

Data were collected from 104 Minnesota swine farms quarantined for pseudorabies virus (PRV) infection. Each herd was serologically evaluated for the presence of antibodies to PRV in finishing pigs. Herd management practices, swine housing design, and disease profiles were described for each farm. Multiple logistic regression analysis was used to determine which factors were associated with circulation of PRV in the finishing pigs of farrow-to-finish farms. Sixty-seven (64%) of the herds had no serologic evidence of PRV circulation in the finishing section, whereas 37 herds (36%) contained at least one PRV seropositive finishing pig. The odds of a given finishing herd being seropositive for PRV were 2.85 times higher if the finishing pigs were housed in confinement (P = 0.01), 2 times higher if Actinobacillus (Haemophilus) pleuropneumoniae was a clinical problem in the herd (P = 0.03), 1.36 times less for each year that passed since the herd quarantine was issued (P = 0.01), 1.74 times higher if clinical signs of PRV were reported (P = 0.04), and 1.52 times higher if animal protein was included in at least one of the rations (P = 0.08).     

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.     

Onset and duration of fecal shedding,cell-mediated and humoral immune responses in pigs after challenge with a pathogenic isolate or attenuated vaccine strain of Lawsonia intracellularis

Little is known about the humoral and, especially, cell-mediated immune response in pigs exposed to Lawsonia intracellularis. The objectives of this study were to investigate the onset and duration of fecal shedding, cell-mediated and humoral immune responses in pigs after challenge with a pathogenic isolate or a commercial live vaccine strain of L. intracellularis. Twenty-four 5-week-old pigs were exposed to 4.4x10(9) organisms of a pathogenic L. intracellularis isolate PHE/MN1-00 (10 pigs), a L. intracellularis live attenuated vaccine strain (10 pigs) or sham inoculum (4 pigs). Fecal, serum and whole blood samples were collected from all animals before exposure and weekly up to 13 weeks post inoculation and tested by PCR, immunoperoxidase monolayer assay serology and an interferon-gamma assay, respectively. One animal from each group was euthanized on day 22 post exposure to confirm infection. Humoral and cell-mediated immune responses were initially detected 2 weeks after exposure in pigs challenged with the pathogenic isolate, and 5 and 4 weeks, respectively, in pigs exposed to the modified-live vaccine group. Humoral and cell-mediated immune responses were still detected in some pigs from both L. intracellularis exposed groups 13 weeks after exposure. Fecal shedding was initially detected 1 week and lasted, intermittently, 12 weeks post exposure in pigs challenged with the pathogenic isolate, while fecal shedding was first detected 2 weeks and lasted, also intermittently, 9 weeks after exposure to the vaccine. In summary, both pathogenic isolate challenged and vaccine exposed pigs demonstrated long-term shedding of and immune responses to L. intracellularis.     

Simultaneous detection of Brachyspira hyodysenteriae, Brachyspira pilosicoli and Lawsonia intracellularis in porcine faeces and tissue samples by multiplex-PCR

Diarrhoea in growing and finishing pigs is usually caused by infectious agents and laboratory diagnosis is a prerequisite for efficient therapy. Cultivation of Brachyspira hyodysenteriae or Brachyspira pilosicoli and detection of Lawsonia intracellularis by means of immunofluorescence tests (IFT) are time-consuming and in some cases lack sensitivity. A multiplex-PCR was designed to detect simultaneously these three pathogens in faeces and tissue samples, allowing the differential diagnosis of dysentery, intestinal spirochaetosis and proliferative enteropathy. Detection limits for B. hyodysenteriae, B. pilosicoli and L. intracellularis were 10(4), 10(2) and 10(3) copies respectively. Agreement between multiplex-PCR and nested-PCR or cultivation was considered substantial to almost perfect. Agreement between multiplex-PCR and IFT in detecting L. intracellularis was only moderate, which was probably related to false-positive results given by IFT. The multiplex-PCR described herein is a valuable tool for the rapid and simultaneous detection of three different pathogens in porcine samples causing enteric diseases.     

Application of real-time PCR for detection of Lawsonia intracellularis and Brachyspira hyodysenteriae in fecal samples from pigs

The aim of the study was to develop and validate real-time PCR method for the quantification of Lawsonia intracellularis and Brachyspira hyodysenteriae in porcine feces. Before the optimization process was performed two different extraction methods were compared to select the more efficient one. Based on the results achieved at this stage the boiling procedure was rejected and a commercially available silica-membrane based method was chosen for further analysis. The primers and the Taqman probe for B. hyodysenteriae and L. intracellularis were based on the sequence of NADH oxidase gene and 16S rDNA gene, respectively. The detection limit of the real-time PCR for suspension of feces inoculated with B. hyodysenteriae and L. intracellularis was determined to be 1.5x10(3) CFU/ml and 6.5x10(1) CFU/ml, respectively. The results of this study demonstrate that our real-time PCR is able to detect low number of B. hyodysenteriae and L. intracellularis cells which is satisfying in routine diagnosis of swine dysentery and proliferative enteropathy. Therefore, it is possible to identify both subclinically infected pigs and those representing an acute form of mentioned diseases. In summary, the quantitative real-time PCR is useful for routine diagnosis of L. intracellularis and B. hyodysenteriae. Compared to conventional PCR, the new validated quantification method based on real-time PCR is fast and with reduced risk of laboratory contamination. The novel technique is specific and even more sensitive than the previously used one. Furthermore, the new real-time PCR enables quick detection and quantification of both pathogens in fecal samples, which helps to estimate the health status of a pig herd.     

The use of quantitative PCR for identification and quantification of Brachyspira pilosicoli, Lawsonia intracellularis and Escherichia coli fimbrial types F4 and F18 in pig feces

This field study explored the cytokine expression in intestinal tissue and serum from 19 diarrhoeic and 9 healthy pigs in herds with a long-time history of Lawsonia intracellularis-infection. The disease, proliferative enteropathy (PE), is associated with diarrhoea and poor performance in growers and haemorrhagic diarrhoea and sudden death in finisher pigs, but the immunopathology is poorly understood. Histopathology, demonstration of L. intracellularis and porcine circovirus type 2 (PCV2) in intestinal tissue by PCR, and detection of serum antibodies to L. intracellularis, were performed. The presence of IL-1β, IL-6, IL-10, IFN-α, IFN-γ, TNF-α and TGF-β in sera was determined by immunoassays, and intestinal mRNA expression of these cytokines plus IL-12p40 was determined by qPCR. Intestinal specimens from pigs with intestinal adenomatosis (n=2), proliferative haemorrhagic enteropathy or swine dysentery (n=2), and controls (n=2) were analysed by a genome wide porcine microarray. The clinical signs of PE were not always supported by the subsequent analyses, and the presence of PCV2 may have contributed to an increased mRNA expression for IFN-γ in intestinal specimens from some pigs. The limited gene expression in the microarray analyses and the limited expression of cytokines in both sera and intestines, indicate that the immune response is poorly activated in the initial course of an infection with L. intracellularis. However, the gene encoding for insulin-like growth factor binding protein 3 (IGFBP-3) was up-regulated in two pigs with prominent mucosal proliferation.