Granulomatous enteritis associated with porcine proliferative enteropathy

An outbreak of proliferative hemorrhagic enteropathy in a commercial pig farm, characterized by granulomatous enteritis, was studied by slaughter checks and by histopathological, histochemical and immunohistochemical studies. Six of the postmortem examined pigs (117-122-day-old) with diagnosis of porcine proliferative enteropathy (PPE) showed granulomatous enteritis and 4.3% of the 465 slaughtered pigs showed gross lesions of PPE. A total of 33 of the 66 ileum samples had histopathological changes, whereas 17 of them had granulomatous enteritis and PPE lesions. Lawsonia intracellularis was immunolabeled in 52 of the ileum samples in epithelial cells and within granulomatous inflammation in Peyer´s patches and in 28 samples of mesenteric lymph nodes. Porcine circovirus type 2 was only detected by immunohistochemistry in 4 ileum samples and in 5 mesenteric lymph nodes. Since there was a strong statistically significant association between granulomatous enteritis and L. intracellularis infection, granulomatous enteritis could be considered as a part of the PPE complex.(AU)

T-2 mycotoxin intoxication in piglets: a systematic pathological approach and apoptotic immunohistochemical studies

An experimental study was performed in order to analyze the histopathological findings of gastrointestinal mucosa and regional lymph-nodes in piglets intoxicated with T-2 toxin as well as the mechanism of T-2 induced apoptosis in the intestinal crypt epithelia. Sixteen piglets were divided into 4 groups receiving a single oral administration of T-2 toxin. Group A: 2.5 mg T-2/kg b.w.; group B: 2 mg T-2/kg b.w.; group C: 1.5 mg T-2/kg b.w.; group D: control group without toxin. Organ lesions were classified in grades 0 to 4 according with severity and were statistically analyzed. Apoptosis was examined in intestinal sections only in groups A and D. Group A piglets showed clinical signs and pathological changes related with those seen in circulatory shock. Microscopic lesions were observed only in pigs from groups A and B. In stomach, lesions consisted of congestion, hemorrhages and necrotic cells in the isthmus and neck regions. Submucosal edema and necrotic crypt epithelial cells were seen in duodenum, jejunum, ileum, cecum and colon. The greatest grade of lesions was observed in colon. In lymph node, grade of lymphocytes depletion and necrosis was significantly higher in cortex than paracortex. Apoptotic bodies were present in intestinal crypt cells, lymphoid cells from lamina propria and ileal Peyer's patches. Apoptosis seems to be the mechanism involved in the development of intestinal lesions.

Serological and histopathological survey of Lawsonia intracellularis infection in 30 Argentinean swine herds

The objectives of this work were: 1) to investigate L. intracellularis antibodies in grower-finisher pigs from 30 herds by immunofluorescent antibody test (IFAT) 2) to evaluate the porcine proliferative enterophaty (PPE) lesions by histopathology, histochemistry (Warthin Starry) and immunohistochemistry (IHC) in ileum samples obtained at slaughterhouse from 10 selected herds, 9 seropositive and 1 control seronegative. At each farm, 30 grower-finisher pigs (18 to 20 weeks old pigs) were randomly selected for blood sampling. The sera were analyzed with a commercial IFAT kit (IleiTest, Elanco Animal Health). The overall percentage of positive pigs was 31.2% (281/900), whereas the percentage of positive farms was 76.7% (23/30). The within-herd mean percentage of positive sera ranged from 27.5 to 53.6%. Only 1 out of the 10 selected farms showed characteristic gross and histopathological lesions at slaughterhouse. On the other hand, 4 farms were positive by immunohistochemistry. In conclusion L. intracellularis infection is widespread among Argentinean farms even though the within-herd percentage was quite variable. Slaughter pigs without microscopic lesions showed immunoreactivity to L. intracellularis.

Neonatal piglets mesocolon edema and colitis due to Clostridium difficile infection: prevalence, clinical disease and pathological studies

Clostridium difficile is a Gram-positive opportunistic anaerobic bacterium found in the soil, water as well as the digestive tract of several species of mammals. Currently in high-health herds and not related with antibiotic treatment, C. difficile has been emerged in association with neonatal catarrhal, fibrinous or purulent colitis in 2 to 7 day-old piglets. Mesocolon edema and colitis with a "volcano" lesion e pathological key marks of C. difficile infection. In farm 1, the prevalence of neonatal piglet mesocolon edema and colitis was evaluated in an extensive study of postmortem preweaning mortality. Lectinhistochemistry pattern of normal colon and colon with edema and colitis were analyzed in order to provide more accurate information related with pathogenesis of C.difficile infection. In farm 2, a clinical description of an outbreak of neonatal colitis in piglets due to C. difficile infection was reported. A total 820 piglets were post-mortem examined, from them, 8 cases were classified as suspected of C. difficile infection (0.1%). Age of affected piglets varied between 3 to 14 days. In all of them, the key mark was the severe mesocolon edema and 2 cases were characterized by focal necrosis and loss of epithelial cells associated with a focal infiltration of neutrophils and macrophages in the lamina propria and lumen like erupted volcano. Lectins SBA and DBA that has affinity to a Gal epitope were negative in normal samples but reacted strongly positive at the glycocalix of the villi enterocytes of the affected samples indicating a change in the carbohydrates pattern of the cells surfaces that might favor the binding of C. difficile toxin A (TcdA). In farm 2, from 11 examined piglets, 6 of them (54%) showed different degree of mesocolon edema and in only 2 of them; volcano lesions were the main histopathological findings. Rectal swab from 8 diarrheic and 5 postmortem examined piglets were surveyed for eltA estl estll and stx2, virulence gens of E. coli and all samples were negative. Clostridium difficile toxins A and B were identified only in the sample with severe gross and microscopic changes. Isolation of difficile was unsuccessfully. Infection of C. difficile is present in Argentinean pig farms. Diagnosis of subclinical infection might be negligent if post-mortem studies of preweaning mortality at weekly intervals are not performed. However, when clinical disease appeared, mortality might be high as it was reported in the farm 2. Comparative lectinhistochemistry studies from field cases added further information of the carbohydrates present on glycocalix of villi enterocytes related with toxin receptors.

Fibrinonecrotic enteritis of piglets in a commercial farm: a postmortem study of the prevalence and the role of lesion associated agents Isospora suis and Clostridium perfringens

The objectives were to determine the prevalence of fibrinonecrotic enteritis (FNE) on a farrow-to-finish farm of 1,000 sows, to categorize the pathological changes, and to to investigate the lesion associated agents Isospora suis and Clostridium perfringens. Causes of preweaning mortality (PWM) were classified into 8 categories including FNE. Obtained data were evaluated for statistical significance by adjusted Chi-square analysis. Samples of FNE were taken for complementary studies including a PCR technique for genotyping toxin genes of Clostridium perfringens from gut samples fixed in 10 percent neutral formalin. From 3,153 piglets examined, less than 1 percent was classified as FNE. FNE prevalence increased progressively from the first to the third week, the last differing statistically from the others. Eighty percent of gut samples with FNE lesions were positive to Isospora suis, when examined by PCR from 9 severe FNE lesions detected 7 positive samples only for a toxin gene, characteristic of C. perfringens type-A.(AU)

Os objetivos deste trabalho foram determinar a prevalência de enterite fibrinonecrótica (EFN) em uma granja tecnificada com 1000 matrizes, classificar as mudanças patológicas e investigar a lesão decorrente da associação dos agentes Clostri-dium perfringens e Isospora suis. As lesões macroscópicas devidas à mortalidade pré-desmame (MPD) foram classificadas em oito categorias incluindo EFN. Os dados obtidos foram avaliados pelo teste Qui-quadrado. Amostras de EFN foram colhidas para estudos complementares incluindo uma técnica de reação em cadeia da polimerase (PCR) para identificação dos genes codificadores de toxinas de C. perfringens a partir de amostras do intestino fixadas em formalina a 10 por cento. Dos 3.153 leitões examinados, menos que 1 por cento foram classificados como EFN. As análises estatísticas revelaram que a EFN aumentou progressivamente a partir da primeira para a terceira semana, sendo que a última semana diferiu estatisticamente das demais. Oitenta porcento das amostras do intestino com EFN foram positivas para I. suis. Por meio da PCR a partir dos 9 casos de EFN severa, 7 foram positivos somente para o gene da toxina alfa, característico de C. perfringens tipo A.(AU)

Mycoplasma suis in naturally infected pigs: an ultrastructural and morphometric study / Mycoplasma suis em suínos naturalmente infectados: um estudo ultra-estrutural e morfométrico

A eperitrozoonose suína é uma doença hemotrópica causada por Eperitrozoon suis, atualmente denominado Mycoplasma suis, uma bactéria extracelular que, aparentemente, adere à membrana dos eritrócitos suínos, induzindo sua deformação e lesionando-os. O presente trabalho busca estabelecer os aspectos estruturais e ultra-estruturais, pouco conhecidos, deste microorganismo. O estudo ultra-estrutural revelou a presença de estruturas correspondentes a túbulos disseminados no soma bacteriano. Observou-se também uma separação variável entre a membrana do microorganismo e a parede do eritrócito. O estudo morfométrico e a localização de M. suis pode permitir especulação sobre seu mecanismo de ação. (AU)

Swine eperythrozoonosis is a haemotrophic disease caused by Eperythrozoon suis, actually called Mycoplasma suis, an extracellular bacterial organism that apparently adheres to pig erythrocyte membrane, inducing its deformation and damage. Since little is known about the ultrastructural and morphometrical aspects of this microorganism, the present work aimed to deal with these issues. The ultrastructural study revealed the presence of structures corresponding to tubules disseminated throughout the soma of M. suis. A variable separation between the microorganism membrane and that of the erythrocyte was also observed. The structural and positional attitude of M. suis could allow speculation about its mechanism of action.(AU)