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.

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.

Serological profile, seroprevalence and risk factors related to Lawsonia intracellularis infection in swine herds from Minas Gerais State, Brazil.

BACKGROUND: Lawsonia intracellularis is the etiologic agent of proliferative enteropathy, which causes diarrhea in several animal species, including swine. Serology can be used both to determine the prevalence of antibodies against a specific pathogen in a herd and to obtain the serological profile, which is used to determine the dynamics of infection in the herd. The objective of this study was to determine the serological profile and seroprevalence of anti-L. intracellularis antibodies in swine herds from intensive production regions of Minas Gerais, Brazil, and to identify the risk factors related to the herd-level seropositivity. RESULTS: A total of 2999 serum samples were collected for this cross-sectional study in the four major regions of intensive swine production in Minas Gerais, Brazil. To obtain better estimates and increase the external validity of the seroprevalence, the sample data were weighted based on the pig population of each herd, the stratum in which the herd was classified and the swine population of the region where each herd was located. A questionnaire was used to identify potential risk factors related to this herd-level seropositivity. The overall weighted prevalence in Minas Gerais was 34.7% (95% confidence interval: 32.12 - 37.20%), and there was no significant difference among the sampled regions, with the seroprevalence rates ranging between 32.06 and 37.66%. Finishing pigs were the most prevalent among the sampled categories. Among the evaluated risk factors, "cleaning before disinfecting" had a negative impact in the seroprevalence (p < 0.05) and was considered a protective factor. CONCLUSIONS: The anti-L. intracellularis antibodies were detected in all of the investigated herds in Minas Gerais, which indicated a wide distribution of the agent in the state. The predominant serological profile was consistent with the dynamics of infection previously observed in pig herds in other countries with similar antimicrobial usage, in which the nursery pigs usually show the lowest seroprevalence and the finishing pigs exhibit the highest. Herds that adopt the practice of "cleaning before disinfection" can decrease their L. intracellularis antibody seropositivity.

Seroprevalence of porcine proliferative enteropathy among wild boars in the Republic of Korea.

BACKGROUND: The importance of the wild boar as a reservoir of Lawsonia intracellularis was assessed by investigating the seroprevalence of this pathogen among wild boars in the Republic of Korea. The extent of exposure to L. intracellularis among wild boars (Sus scrofa coreanus) was monitored by a country-wide serological survey using an immunoperoxidase monolayer assay. RESULTS: In this study, antibodies to L. intracellularis were observed in 165 of 716 clinically healthy wild boars tested. The overall apparent prevalence calculated directly from the sample and the true prevalence calculated based on the accuracy of the test method were 23.0% (95% confidence interval: 20.0-26.3%) and 25.6% (95% confidence interval: 23.9-27.2%), respectively. Serologically positive animals were found in all the tested provinces. CONCLUSIONS: Our results confirm that L. intracellularis is present in the wild boar population worldwide, even in Far East Asia. Despite the high seroprevalence shown in wild boars, further studies are warranted to evaluate their potential as a reservoir species because seroprevalence does not prove ongoing infection nor shedding of the bacteria in amounts sufficient to infect other animals. It should also be determined whether the wild boar, like the domestic pig, is a natural host of L. intracellularis.

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.

Infection of juvenile falcons (Falco spp.) with intestinal Lawsonia intracellularis.

Intestinal infection of many host species with Lawsonia intracellularis are widely reported. Analyses of infections among carnivorous falcons have not previously been reported. Fifty juvenile captive falcons (Falco spp.) with or without Lawsonia infection were investigated in the United Arab Emirates, including clinical laboratory methods. Fresh intestinal biopsy samples were analysed by microbiological techniques for Lawsonia and other bacteria and by standard parasitological and pathological methods. Lawsonia intracellularis infection was diagnosed by microbiological examination and qPCR in 10 of 50 juvenile falcons at case examination. Seven of these 10 falcons were of normal clinical appearance, and the other three had other contributing factors to ill-thrift. A range of other conditions were noted in 40 case control falcons. This first report of Lawsonia infection in falcons suggests that the agent may have a limited contribution to clinical disease in these birds, including ill-thrift syndromes. This lack of clinical disease association mimics that noted among Lawsonia infections recorded in other avian families.

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.

Productivity parameters, antimicrobial consumption, and prevalence of enteric pathogens before and after intramuscular vaccination against Lawsonia intracellularis in naturally infected Danish weaner and finisher pig herds.

In Danish pig production, gastro-intestinal diseases account for most of the antimicrobials (AM) used in growing pigs. Diarrhoea is most frequently caused by Lawsonia intracellularis (LI), Brachyspira pilosicoli (BP), E coli fimbria type F4 (F4) and E. coli fimbria type F18 (F18). With a new LI vaccine available from 2019, it was relevant to investigate the effect of this vaccine in a Danish field study including both weaner and finisher sites. The aim was to evaluate the efficacy of Porcilis® Lawsonia Vet. in naturally LI-infected pig herds by comparing of productivity parameters, AM consumption and dynamics of enteric pathogens over two 6-months periods before and after LI vaccination. Further, faecal sock samples were collected from each site before and after vaccination and analysed by qPCR for excretion levels of LI, BP, F18 and F4. In total, 28 weaner and 41 finisher sites were included in the study. Vaccination reduced Feed Conversion Ratio by 0.12 Feed Unit/kg (p = 0.029) and 0.08 Feed Unit/kg (p = 0.005) in weaners and finishers, respectively. Increased Average Daily Weight Gain of 45.6 gr./day (p < 0.001) was found in the finishers. Mortality risk fell by 8.8% in weaners (RR = 0.912; p < 0.001). AM prescriptions for oral group treatments were reduced by 38.8% active compound/kg pig produced (p = 0.005) or 33.3% Weighted Animal Daily Doses per 100 animals per day in finishers (p = 0.004). LI prevalence was reduced in weaners and finishers (both p < 0.001) and BP prevalence was reduced in finishers (p = 0.043). Mean excretion levels of LI and BP decreased at weaner sites (-1.32 and -1.02 log(10) copies/gr faeces, respectively; both p < 0.001) and at finisher sites (-1.04 and -1.16 log(10) copies/gr faeces, respectively; both p < 0.001). Prevalence and excretion levels of F18 and F4 were unaffected by LI vaccination. In conclusion, vaccination against LI using Porcilis® Lawsonia Vet. improved productivity parameters, cut AM consumption, and reduced prevalence and excretion levels of LI and BP in naturally LI-infected pig herds.

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.

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.

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.

High Seroprevalence Against Lawsonia intracellularis Among Adult Horses in Belgium.

Lawsonia intracellularis (LI) is an obligate intracellular gram-negative rod causing equine proliferative enteropathy (EPE). Occasional cases of EPE have been reported in foals living in Belgium, but the seroprevalence of equine LI in this country is unknown. The target population included clinically healthy adult horses, whose blood samples were collected and analyzed for specific IgG antibodies against LI using a blocking enzyme-linked immunosorbent assay test. The results were expressed as percentage of inhibition (PI). Samples that had a PI <20% were judged as negative, those between 20 and 30% as inconclusive, and those >30% were considered positive. A total of 356 blood samples were analyzed with 352 horses (98.8%) testing positive, 2 horses (0.6%) testing negative, and 2 horses (0.6%) showing inconclusive results. The large percentage of seropositive samples obtained in this study confirms a widespread exposure of Belgian horses to LI.

Temporal detection of Lawsonia intracellularis using serology and real-time PCR in Thoroughbred horses residing on a farm endemic for equine proliferative enteropathy.

The goals of this study were to evaluate titers of antibodies against Lawsonia intracellularis in 68 resident broodmares from a farm known to be endemic for equine proliferative enteropathy (EPE) and to evaluate maternal antibodies, occurrence of seroconversion and fecal shedding in their foals. Serum samples collected from mares at delivery and from foals pre- and post-colostrum ingestion and monthly thereafter were tested for the presence of L. intracellularis antibodies by immunoperoxidase monolayer assay (IPMA). Further, feces collected from mares at delivery and foals post-partum and monthly thereafter were assayed for L. intracellularis using real-time PCR. Thirty-seven mares (54.4%) had detectable antibody titers (> or =60) against L. intracellularis by IPMA at the time of foaling. Passive transfer of colostral antibodies against L. intracellularis was documented in 37 foals (54.4%) and the colostral antibodies remained detectable in the serum of foals for 1-3 months. Overall, 22 foals (33.3%) showed evidence of natural exposure to L. intracellularis throughout the study period, however, none of the study foals developed signs compatible with EPE. The serological results showed that mares residing on a farm known to be endemic for EPE are routinely exposed to L. intracellularis and that antibodies against L. intracellularis are passively transferred to foals.

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.

Lawsonia intracellularis associated equine proliferative enteropathy in Danish weanling foals.

BACKGROUND: Lawsonia intracellularis, an obligate intracellular bacterium, causes equine proliferative enteropathy, mainly in horses around weaning. This disease is rarely reported in the Scandinavian countries. RESULTS: Five cases of equine proliferative enteropathy were diagnosed between 2008-2016 at the University of Copenhagen Large Animal Teaching Hospital. Cases were Danish Warmbloods and a Friesian horse, aged 6-7 months, presenting with typical clinical signs of lethargy, poor body condition, pyrexia and diarrhea. Clinical pathology was consistent with previous reports of severe hypoalbuminemia and leukocytosis. Diagnosis was confirmed by fecal polymerase chain reaction, serum immunomonolayer peroxidase assay and/or immunofluorescence and fluorescence in situ hybridization performed on formalin-fixed ileum samples. Concurrent intestinal parasitism was present in all five cases. Treatment consisted of antimicrobial therapy, anti-inflammatories, intravenous crystalloids and plasma. Three foals were euthanised due to deterioration and poor response to treatment, one with complications of septic arthritis and Strongylus vulgaris associated intestinal infarct. The other two foals survived and were reported by the owners to be healthy on long-term follow-up. CONCLUSIONS: Equine proliferative enteropathy is a disease to consider in young horses presenting with diarrhea and hypoproteinemia in Denmark.

Oral fluid for detection of exposure to Lawsonia intracellularis in naturally infected pigs.

To demonstrate the utility of oral fluid (OF) for indirect diagnostic detection of Lawsonia intracellularis (Li), 15 pig farms were studied. Serum and fecal samples were collected from 20 animals from five different age groups on each farm. OF samples were collected from animals in two pens of the same age groups. Serum and OF samples were analyzed in an immunoperoxidase in monolayer assay (IPMA) for the detection of anti-Li immunoglobulin G (IgG) and A (IgA). Compatible results were found between PCR and IgG in OF in four of the five ages evaluated. Simultaneous detection of IgG in serum and OF was mainly observed on farms showing clinical signs suggestive of porcine proliferative enteropathy (PPE). These findings demonstrate the potential usefulness of OF in detecting anti-Li antibodies as a diagnostic tool that can be used to monitor PPE in herds with clinical signs compatible with the disease.

Detection of Lawsonia intracellularis by real-time PCR in the feces of free-living animals from equine farms with documented occurrence of equine proliferative enteropathy.

The objective of this study was to determine whether Lawsonia intracellularis was present in the feces of free-living animals collected on two equine premises with documented occurrence of equine proliferative enteropathy (EPE). Fresh feces from black-tailed jackrabbits (Lepus californicus, n=100), striped skunks (Mephitis mephitis, n=22), feral cats (Felis catus, n=14), Brewer's Blackbirds (Euphagus cyanocephalus, n=10), Virginian opossums (Didelphis virginiana, n=9), raccoons (Procyon lotor, n=4), California ground squirrels (Spermophilus beecheyi, n=3), and coyotes (Canis latrans, n=2) were collected from August 2006 to January 2007 either from the ground while walking the premises or after trapping the animals using live traps. Nucleic acid purified from feces was directly processed for polymerase chain reaction (PCR) analysis using a real-time PCR assay targeting the aspartate ammonia lyase gene of L. intracellularis. Purified DNA samples were also precipitated, preamplified for L. intracellularis, and analyzed using the same real-time PCR assay, to increase the detection limit to one L. intracellularis organism per extracted sample. Feces from jackrabbits, striped skunks, Virginian opossums, and coyotes tested PCR positive for L. intracellularis, whereas all feces from feral cats, Brewer's Blackbirds, raccoons, and ground squirrels tested PCR negative for L. intracellularis. PCR testing on DNA extracted directly from feces was positive for L. intracellularis in six of 164 fecal samples. When DNA purification from feces was followed by a precipitation and preamplification step, five additional fecal samples tested PCR positive for L. intracellularis (11/164). The largest number of PCR positive L. intracellularis fecal samples was observed in striped skunks, followed by Virginian opossums, jackrabbits, and coyotes. This is the first description of L. intracellularis in these four species. Because the fecal samples were collected at equine farms with confirmed cases of EPE, striped skunks, Virginian opossums, jackrabbits, and coyotes may act as potential sources of infection to susceptible weanlings.

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.

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.

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.