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Porcine circovirus type 3 (PCV3) is considered a new circovirus and since it first description has been widely reported in most of the swine-producing countries. Multisystemic inflammation and reproductive failure are consistent and concerning issues associated with PCV3 infection. This report describes the clinical and pathological features of a chronic reproductive disorder in a swine herd in Argentina associated with the presence of PCV3. Mummified (n = 42) and stillborn piglets (n = 20) from a case of chronic reproductive disorder (Study A) and mummified and stillborn piglets (n = 141) from normal deliveries (Study B) were retrospectively assessed for the presence of multiple reproductive pathogens (PCV3, PCV2, ADV, PPV, Leptospira spp. and Brucella spp). On study, A PCV3 and PPV were detected in 15 and 8 pools, respectively, with a coinfection rate of 100% in all PPV-positive cases. Three out of 131 foetuses from three different sows from Study B were positive only for PCV3. Histological evaluation of hearts from stillborn also showed lesions similar to those previously described in the literature for PCV3-reproductive disease. Partial genome of PCV3 was amplified and phylogenetic analysis showed that strains of Study A and B clustered within the PCV3a and PCV3b clades, respectively. This study demonstrates, for the first time, the PCV3 has been circulating in Argentina at least since 2016 and its potential role in reproductive disorders. Further studies are warranted to determine the role of PCV3 in the reproductive disease complex and its prevalence in the swine industry in Argentina., Facultad de Ciencias Veterinarias

Over the last 30 years, diseases caused by emerging swine viruses (ESV) have acquired great relevance, more than in other species. Diseases caused by porcine reproductive and respiratory syndrome virus (PRRSv), high pathogenicity porcine epidemic diarrhea virus (PEDv), porcine circovirus type 2 (PCV-2), and influenza virus H1N1pdm09 had great economic impact. Others, however, such as porcine enteroviruses, porcine toroviruses (PToV), porcine sapelovirus (PSV), porcine bocavirus (PBoV), porcine kobuvirus (PKBV), and porcine Torque teno sus virus (TTSuV) are mostly subclinical in swine herds. Furthermore, novel emerging viruses, such as SENECA virus, atypical porcine pestivirus (APPV), PCV-3, SADS-CoV, influenza D, and others with regional or worldwide distribution constitute a new challenge for researchers and practicing veterinarians. Instituto de Virología Fil: Perfumo, Carlos Juan. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Cátedra de Patología Especial; Argentina Fil: Pereda, Ariel Julian. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología. Laboratorio de Virología de Aves y Cerdos; Argentina Fil: Jongkaewwattana, Anan. National Center for Genetic Engineering and Biotechnology (BIOTEC); Tailandia Fil: Chen, Zhenhai. Yangzhou University. College of Veterinary Medicine; China Fil: Perez, Daniel Roberto. University of Georgia. College of Veterinary Medicine. Poultry Diagnostic and Research Center; Estados Unidos Fil: Ma, Jingyun. South China Agricultural University. College of Animal Science; China

This study uses network analysis to evaluate how swine movements in Argentina could contribute to disease spread. Movement data for the 2014–2017 period were obtained from Argentina's online livestock traceability registry and categorized as follows: animals of high genetic value sent to other farms, animals to or from markets, animals sent to finisher operations and slaughterhouse. A network analysis was carried out considering the first three movement types. First, descriptive, centrality and cohesion measures were calculated for each movement type and year. Next, to determine whether networks had a small‐world topology, these were compared with the results from random Erdös–Rényi network simulations. Then, the basic reproductive number (R0) of the genetic network, the group of farms with higher potential for disease spread standing at the top of the production chain, was calculated to identify farms acting as super‐spreaders. Finally, their external biosecurity scores were evaluated. The genetic network in Argentina presented a scale‐free and small‐world topology. Thus, we estimate that disease spread would be fast, preferably to highly connected nodes and with little chances of being contained. Throughout the study, 31 farms were identified as super‐spreaders in the genetic network for all years, while other 55 were super‐spreaders at least once, from an average of 1,613 farms per year. Interestingly, removal of less than 5% of higher degree and betweenness farms resulted in a >90% reduction of R0 indicating that few farms have a key role in disease spread. When biosecurity scores of the most relevant super‐spreaders were examined, it was evident that many were at risk of introducing and disseminating new pathogens across the whole of Argentina's pig production network. These results highlight the usefulness of establishing targeted surveillance and intervention programmes, emphasizing the need for better biosecurity scores in Argentinean swine production units, especially in super‐spreader farms. info:eu-repo/semantics/acceptedVersion

Este compendio está dirigido a estudiantes avanzados de Medicina Veterinaria así como a jóvenes veterinarios con interés en la clínica y sanidad de los cerdos. En esta obra, se ha volcado la experiencia de un grupo de docentes-investigadores del Laboratorio de Patología Especial Veterinaria y de la Cátedra de Medicina Porcina así como de otras cátedras de la Facultad Ciencias Veterinarias, UNLP, de la Facultad de Ciencias Veterinarias, UNCPB y de veterinarios privados. El compendio condensa: - Los trabajos de laboratorio y de campo en el área de sanidad porcina realizados por los autores y publicados en revistas y congresos nacionales e internacionales. - Las tesis sobre sanidad porcina dirigidas por los docentes del Laboratorio de Patología Especial Veterinaria. - Los cursos de posgrado realizados sobre enfermedades emergentes y reemergentes de los cerdos y otros relacionados a la sanidad porcina. - La experiencia docente de los autores a nivel de grado y posgrado., Facultad de Ciencias Veterinarias

The pig industry is growing very fast in Argentina with an increasing need for replacement animals, feedstuff and transportation of animals. One of the main competitive advantages of the Argentinian pig industry is its being free of most major pig diseases. Within this context, applying measures aimed to reduce the risk of introduction and spread of pathogens is critical. The aim of the present study was to assess the biosecurity of Argentinian pig farms. Two types of farms were assessed: firstly, all official suppliers of high-genetic-value (n = 110) and secondly, a sample from commercial farms (n = 192). Data on the external and internal biosecurity practices applied on the farms was collected with a questionnaire. Data was analysed using a correspondence analysis and a hierarchical clustering analysis, which allowed identification of types of farms with regard to the biosecurity measures applied. Key variables characterizing the clusters were identified through an indicator value analysis. In addition, the external biosecurity of the farms was evaluated by using risk assessment tools with respect to the potential introduction of porcine epidemic diarrhoea virus. Results made evident three clusters: the first one which, amongst other measures, applied several barriers to prevent the entry of people, trucks and other vehicles, and could be considered as a group of high biosecurity, and the two other groups which applied a lower number of external and internal biosecurity measures. The results of the risk assessment showed that the routes with the highest risk of disease introduction were: replacement animals, vehicles transporting feed or animals, and visitors. The assessment of the external biosecurity showed that most Argentinian farms were not prepared for the contingency of a pathogen such as porcine epidemic diarrhoea virus. Special efforts should be made in official suppliers of high-genetic-value farms with poor biosecurity scores since they are at the top of the pig production chain and can be key for the spread of diseases. info:eu-repo/semantics/acceptedVersion

Background: In 2014, a notification of porcine transmissible gastroenteritis virus (TGEV) was made by the National Services of Animal Health of Argentina (SENASA) to the World Organization of Animal Health (OIE). The notification was based on a serological diagnosis in a small farm with a morbidity rate of 2.3% without enteric clinical signs. In order to determine if TGEV was circulating before the official report, a retrospective study on cases of neonatal diarrhea was performed. The selection criteria was a sudden increase in mortality in 1- to 21-day-old piglets with watery diarrhea that did not respond to antibiotics. Based on these criteria, three clinical cases were identified during 2010–2015. Results: All animals that were evaluated presented histological lesions consistent with enteric viral infection. The feces and ultrathin sections of intestine that were evaluated by electron microscopy confirmed the presence of round particles of approximately 80 nm in size and characterized by finely granular electrodense nucleoids consistent with complete particles of coronavirus. The presence of the TGEV antigen was confirmed by monoclonal specific immunohistochemistry, and final confirmation of a metabolically-active virus was performed by in situ hybridization to detect a TGE mRNA encoding spike protein. All sections evaluated in this case were negative for PEDV and rotavirus A. Conclusions: This is the first case series describing neonatal mortality with etiological confirmation of TGEV in Argentina. The clinical diagnosis of TGEV infections in endemic regions is challenging due to the epidemiological distribution and coinfection with other enteric pathogens that mask the clinical presentation., Facultad de Ciencias Veterinarias

Swine farms provide a dynamic environment for the evolution of influenza A viruses (IAVs). The present report shows the results of a surveillance effort of IAV infection in one commercial swine farm in Argentina. Two cross-sectional serological and virological studies (n = 480) were carried out in 2011 and 2012. Virus shedding was detected in nasal samples from pigs from ages 7,21 and 42-days old. More than 90% of sows and gilts but less than 40% of 21-days old piglets had antibodies against IAV. Inaddition, IAV was detected in 8/17 nasal swabs and 10/15 lung samples taken from necropsied pigs. A subset of these samples was further processed for virus isolation resulting in 6 viruses of the H1N2 subtype (δ2 cluster). Pathological studies revealed an association between suppurative bronchopneumonia and necrotizing bronchiolitis with IAV positive samples. Statistical analyses showed that the degree of lesions in bronchi, bronchiole, and alveoli was higher in lungs positive to IAV. The results of this study depict the relevance of continuing long-term active surveillance of IAV in swine populations to establish IAV evolution relevant to swine and humans., Facultad de Ciencias Veterinarias

Ganglioneuromatosis (GNM) is a rare condition characterized by the benign proliferation of ganglion cells, nerve fibres and supporting cells of the enteric nervous system. Necropsy examination of a female piglet weighing 4 kg revealed a well-demarcated 20 cm segment of terminal ileum with thickening of the wall. Microscopically, the lamina propria was infiltrated by enteric glial cells and large ganglion cells. Within the submucosal and muscular layers, aggregates of neurons were interlaced by Schwann cells and enteric glial cells arranged in concentric rings. Immunohistochemically, the neurons were weakly labelled for S-100 and neuron-specific enolase, Schwann cells expressed S-100 and vimentin and enteric glial cells expressed glial fibrillary acidic protein and S-100. Pathological and immunohistochemical findings supported the diagnosis of ileal GNM. Fil: Quiroga, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina Fil: Lozada, María Inés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina Fil: Madariaga, Gonzalo Julián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina Fil: Cappuccio, Javier Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina Fil: Machuca, Mariana Alejandra. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina Fil: Barrales, H.. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina Fil: Pérez, Estefanía Marisol. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina Fil: Perfumo, C. J.. Universidad Nacional de la Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Laboratorio de Patología Especial Veterinaria "Dr. Bernardo Epstein"; Argentina

Summary An ultramicroscopic study of early lesions in experimentally produced pneumonia in two pigs induced by intranasal inoculation of Haemophilus pleuropneumoniae serotype 1, was performed. Samples were obtained at 24 hours and 48 hours post-inoculation (p. i.). Both types of epithelial cells showed marked degenerative changes of a non-specific nature 24 hours p.i. The capillaries were dilated and filled with packed erythrocytes in different stages of disintegration. At 24 hours p. i. only slight degenerative changes were found in the capillary endothelium, while at 48 hours degenerative changes were a regular finding. The thrombi formed in the capillaries and identified in the light microscope as appearing to consist of fibrin were in fact composed of disintegrated erythrocytes. The vascular changes found in the initial stages had similarities with the Shwartzman reaction. The inflammatory cells found in connection with the degenerative and exudative changes were identified as macrophages and occasional neutrophils. The pathogenesis of the ultrastructural changes induced by Haemophilus pleuropneumoniae is discussed, based on our results as well as those reported in the literature. Zusammenfassung Pleuropneumonie der Schweine durch Haemophilus pleuropneumoniae III. Elektronenmikroskopische Studie Fruhe Lasionen einer Pneumonie beim Schwein, experimentell durch intranasale Inokulation mit Haemophilus pleuropneumoniae Serotyp I induziert, wurden elektronenmikroskopisch untersucht. Untersuchungsproben wurden nach 24 und 48 Stunden gewonnen. Die Kapillaren waren erweitert und mit Erythrozyten in verschiedenen Stadien der Auflosung gefullt. 24 Stunden nach der Inokulation liesen sich nur leichte degenerative Veranderungen am Kapillarendothel feststellen, wahrend nach 48 Stunden Degenerationen die Regel waren. Die in den Kapillaren entstandenen Thromben, lichtmikroskopisch als fibrinos gedeutet, setzten sich aus aufgelosten Erythrozyten zusammen. Die Gefasveranderungen in den Anfangsstadien ahnelten der Shwartzman-Reaktion. Die in Verbindung mit den degenerativen und exudativen Veranderungen auftretenden Entzundungszellen wurden als Makrophagen und gelegentliche Neutrophile identifiziert. Die Pathogenese der durch Haemophilus pleuropneumoniae hervorgerufenen ultra-strukturellen Veranderungen werden aus der Basis eigener Ergebnisse sowie der vorliegenden Literatur diskutiert. Resume Pleuropneumonie du porc due a Haemophilus pleuropneumoniae III. Etude au microscope electronique Les lesions precoces d'une pneumonie chez le pore induite experimentalement par inoculation intranasale d'Haemophilus pleuropneumoniae serotype I ont ete examinees au microscope electronique. Les echantillons ont ete preleves apres 24 et 48 heures. Les capillaires etaient elargis et remplis d'erythrocytes a differents stades de lyse. Seules de legeres lesions degeneratives de l'endothelium capillaire ont ete mises en evidence 24 heures apres l'inoculation alors que des degenerescences furent la regle apres 48 heures. Les thrombus constates dans les capillaires, caracterises de fibrineux au microscope optique, se composaient d'erythrocytes lyses. Les lesions vasculaires ressemblaient au debut a la reaction de Shwartzman. Les cellules inflammatoires en liaison avec les lesions degeneratives et exsudatives ont ete identifiees comme des macrophages et parfois des neutrophiles. La pathogenese des lesions ultrastructurelles dues a Haemophilus pleuropneumoniae est discutee sur la base de ces resultats et de la litterature existante. Resumen Pleuropneumonia porcina producida por Haemophilus pleuropneumoniae III. Estudio con el microscopio electronico Al microscopio electronico se estudiaron las lesiones precoces de una pneumonia en porcinos, inducida por via experimental mediante inoculacion intranasal con Haemophilus pleuropneumoniae serotipo I. Las muestras a examinar se obtuvieron al cabo de 24 y 48 horas. Los capilares se hallaban dilatados y llenos de eritrocitos empacados en estadios diferentes de desintegracion. 24 horas despues de la inoculacion se hallaron solo cambios degenerativos ligeros en el endotelio capilar, mientras que a las 48 horas los cambios degenerativos eran un hallazgo regular. Los trombos formados en los capilares e identificados al microscopio electronico como fibrinosos estan compuestos, de hecho, por eritrocitos desintegrados. Los cambios vasculares hallados en los estadios iniciales tienen semejanzas con la reaccion de Shwartzman. Las celulas inflamatorias encontradas en conexion con los cambios degenerativos y exudativos fueron identificadas como macrofagos y ocasionalmente neutrofilos. Se discute la patogenia de los cambios ultraestructurales inducidos por Haemophilus pleuropneumoniae, basandonos en nuestros resultados asi como en los hallados en la bibliografia.

In June-July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argentina. Molecular analysis indicated that the virus was genetically related to the pandemic (H1N1) 2009 influenza virus strain. The outbreak presumably resulted from direct human-to-pig transmission., Facultad de Ciencias Veterinarias

Enterotoxigenic Escherichia coli (ETEC) is the major pathogen responsible for neonatal diarrhea, postweaning diarrhea, and edema disease in pigs. Although it can be harmless, ETEC is also present in the intestines of other animal species and humans, causing occasional diarrhea outbreaks. The evaluation of this pathogen’s presence in food sources is becoming an increasingly important issue in human health. In order to determine the prevalence of ETEC in nondiarrheic pigs, 990 animals from 11 pig farms were sampled. Using end-time polymerase chain reaction (PCR), eltA, estI genes, or both, were detected in 150 (15.2%) animals. From the positive samples, 40 (26.6%) ETEC strains were isolated, showing 19 antibiotic-resistance patterns; 52.5% of these strains had multiple antibiotic resistances, and 17.5% carried the intI2 gene. The most prevalent genotypes were rfbO157/estII/aidA (32.5%) and estI/estII (25.0%). The estII gene was identified most frequently (97.5%), followed by estI (37.5%), astA (20.0%), and eltA (12.5%). The genes coding the fimbriae F5, F6, and F18 were detected in three single isolates. The aidA gene was detected in 20 ETEC strains associated with the estII gene. Among the isolated ETEC strains, stx2e/estI, stx2e/estI/estII, and stx2e/estI/estII/intI2 genotypes were identified. The ETEC belonged to 12 different serogroups; 37.5% of them belonged to serotype O157:H19. Isolates were grouped by enterobacterial repetitive intergenic consensus–PCR into 5 clusters with 100.0% similarity. In this study, we demonstrated that numerous ETEC genotypes cohabit and circulate in swine populations without clinical manifestation of neonatal diarrhea, postweaning diarrhea, or edema disease in different production stages. The information generated is important not only for diagnostic and epidemiological purposes, but also for understanding the dynamics and ecology of ETEC in pigs in different production stages that can be potentially transmitted to humans from food animals. Fil: Moredo, Fabiana A.. Universidad Nacional de la Plata. Facultad de Cs.veterinarias. Departamento de Microbiologia. Catedra de Microbiologia; Argentina Fil: Piñeyro Piñeiro, Pablo Enrique. University of Iowa; Estados Unidos Fil: Márquez, Gabriela C.. Virginia Polytechnic Institute; Estados Unidos Fil: Sanz, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina Fil: Colello, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina Fil: Etcheverría, Analía Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina Fil: Padola, Nora L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina Fil: Quiroga, Maria A.. Universidad Nacional de la Plata. Facultad de Cs.veterinarias. Departamento de Patologia. Laboratorio de Patolog. Espec. Veterinaria "dr. Bernardo Epstein"; Argentina Fil: Perfumo, Carlos J.. Universidad Nacional de la Plata. Facultad de Cs.veterinarias. Departamento de Patologia. Laboratorio de Patolog. Espec. Veterinaria "dr. Bernardo Epstein"; Argentina Fil: Galli, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Genética Veterinaria "Ingeniero Fernando Noel Dulout"; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentina Fil: Leotta, Gerardo Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Genética Veterinaria "Ingeniero Fernando Noel Dulout"; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentina

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., Facultad de Ciencias Veterinarias

Objetivos. Investigar la presencia Erysipelothrix rhusiopathiae en cerdos de las categorías crecimiento y engorde con lesiones sistémicas no cutáneas compatibles con las de mal rojo (MR) provenientes de dos granjas, situadas en la provincia de Buenos Aires, Argentina. Materiales y Métodos. Muestras de tonsilas, corazón (endocardio), bazo, riñón y líquido articular con lesiones compatibles con las del mal rojo se inocularon en caldo ESB y se repicaron en medio sólido MBA. A partir de colonias similares a las del género Erisipelothrix, se realizaron tinción de Gram y pruebas fisiológicas y bioquímicas. La identificación serológica se llevó a cabo por la prueba de inmunodifusión doble en gel de agarosa enfrentando antígenos extractados de las cepas en estudio contra sueros hiperinmunes de los 28 serotipos de referencia de E. rhusiopathiae. Resultados. Se aisló E. rhusiopathiae de dos cerdos a partir de tonsilas (sin lesiones aparentes), bazo (con esplenomegalia), endocardio valvular con lesiones de endocarditis) y exudado articular no purulento). En otro animal sólo se lo aisló de exudado articular. Las tres cepas de E. rhusiopathiae correspondieron al serotipo 10. El aislamiento de E. rhusiopathiae se dificultó debido al crecimiento de bacterias de los géneros Lactobacillus spp y Enterococcus spp que enmascararon o compitieron en el desarrollo de las colonias. Discusión. El E. rhusiopathiae serotipo 10 es raramente aislado de cerdos y no se lo ha asociado cuadros clínicos de erisipela. El aislamiento E. rhusiopathiae serotipo 10 de lesiones sistémicas no cutáneas compatibles con las del MR del cerdo,constituye la primera referencia de la infección del cerdo por E. rhusiopathiae en el país así como de la patogenicidad de dicho serotipo.

Apoptotic index (AI) of the gastrointestinal mucous epithelia was examined in mice at 8, 16, 24 and 48 hours after oral inoculation (HAI) of T-2 toxin (10mg/kg). In the fundic region of the stomach, AI prominently increased at 8 HAI and deceased thereafter in the foveolae gastricae while it started to increase slowly and became prominent at 24 HAI in the glandular base. AI in the glandular neck was constantly low. On the other hand, in the intestinal crypt epithelia, AI prominently increased at 8 HAI in all regions examined (duodenum, ileum, cecum and colon), and thereafter decreased with the lapse of time. AI was clearly higher in the small intestine than in the large one especially in the early stage. Mitotic index (MI) examined was drastically decreased at 8 HAI when AI prominently increased, and thereafter turned to recover in the lapse of time. However AI after T-2 toxin inoculation was not always proportional to MI before T-2 toxin inoculation. The sequence of and the regional difference in AI in the gastrointestinal mucous epithelia after T-2 toxin intoxication was first clarified in the present study.

Angiostrongylus is a metastrongylid nematode genus that includes species found in carnivores, rodents, and occasionally primates (including humans). About 100 species of wild sigmodontine rodents occur in Argentina, 16 of which are species of Akodon. The lungs of Akodon azarae and Akodon dolores from Sierra de la Ventana, Buenos Aires, Argentina, were examined, and 2 of 10 A. dolores specimens were positive for angiostrongylosis, showing macroscopic lesions of verminous pneumonia. Adults found were identified as Angiostrongylus morerai. Histopathology of the lungs revealed multiple nodules in the interstitium, alveoli, and vessels, resulting in interstitial fibrosis and the destruction of small capillaries and arterioles. Since extensive pathology in the lung was noted here from only 2 adults, it is probable that heavier infections may cause mortality in their hosts. This is the first record of this nematode species from A. dolores , expanding its geographic distribution to the southwest of Buenos Aires Province, and the first description of the histopathology of larval angiostrongylosis in a wild rodent from South America.

Renal changes in mice daily treated with low doses of ochratoxin A (OA; 50-400μg/kg) for up to 4 weeks were investigated by electron microscope. Except the mice treated with 50μg/kg of OA for 4 weeks, all treated mice showed the following changes in the epithelial cells of Henle's loop: (1) degeneration of mitochondria, (2) increment of endoplasmic reticula, and (3) increase in the number and size of lysosomes and myelin figures., Facultad de Ciencias Veterinarias

Peripheral neuroblastoma (PNB) is a rare neoplasia derived from neuroepithelial cells. PNB typically presents as a greyish mass, composed of round cells with features of neuronal differentiation. Necropsy, performed on a 1-day-old piglet, revealed a mass craniodorsally located in the abdominal cavity. Histologically, the predominant population consisted of small round to ovoid cells with scanty cytoplasm and dark round nuclei, besides, there were larger neurone-like cells. Neurone-specific enolase and S-100 protein were immunohistochemically detected, while glial fibrillary acidic protein was negative. Histological and immunohistochemical findings substantiated the diagnosis of a grade II peripheral neuroblastoma. This seems to be the first description of a PNB in a newborn piglet.

Porcine circovirus type 2 (PCV-2) has been associated with syndromes grouped by the term porcine circovirus associated diseases (PCVAD). The PCV-2 isolates have been grouped into two major groups or genotypes according to their nucleotide sequence of whole genomes and/or ORF-2: PCV-2b, which have, in turn, been subdivided into three clusters (1A–1C), and PCV-2a, which has been subdivided into five clusters (2A–2E). In the present study, we obtained 16 sequences of PCV-2 from different farms from 2003 to 2008, from animals with confirmatory diagnosis of PCVAD. Since results showed an identity of 99.8% among them, they were grouped within a common cluster 1A-B. This preliminary study suggests a stable circulation of PCV-2b among the Argentinean pig population., Facultad de Ciencias Veterinarias

Sporadic outbreaks of human H3N2 influenza A virus (IAV) infections in swine populations have been reported in Asia, Europe and North America since 1970. In South America, serological surveys in pigs indicate that IAVs of the H3 and H1 subtypes are currently in circulation; however, neither virus isolation nor characterization has been reported. In November 2008, an outbreak of respiratory disease in pigs consistent with swine influenza virus (SIV) infection was detected in Argentina. The current study describes the clinical epidemiology, pathology, and molecular and biological characteristics of the virus. Phylogenetic analysis revealed that the virus isolate shared nucleotide identities of 96-98% with H3N2 IAVs that circulated in humans from 2000 to 2003. Antigenically, sera from experimentally inoculated animals cross-reacted mainly with noncontemporary human-origin H3N2 influenza viruses. In an experimental infection in a commercial swine breed, the virus was of low virulence but was transmitted efficiently to contact pigs and caused severe disease when an infected animal acquired a secondary bacterial infection. This is the first report of a wholly human H3N2 IAV associated with clinical disease in pigs in South America. These studies highlight the importance of two-way transmission of IAVs and SIVs between pigs and humans, and call for enhanced influenza surveillance in the pig population worldwide., Facultad de Ciencias Veterinarias

The aim of this surveillance was to study both Salmonella spp. shedding patterns and the time course of serological response in farrow-to-finish reared pigs from a subclinically infected farm. Antimicrobial resistance profile, molecular subtyping, and the relationship among the isolates were determined by pulsed-field gel electrophoresis (PFGE). A farrow-to-finish farm of 6000 sows, with a history of Salmonella Typhimurium septicemia, was selected. A longitudinal bacteriological and serological study was conducted in 25 sows before farrowing (M=S1) and in 50 offspring at 21 (M=S2), 35 (M=S3), 65 (M=S4), 86 (M=S5), 128 (M=S6), and 165 (M=S7) days of age. Serum antibodies were tested using Herdcheck Swine Salmonella antibody test kit (Idexx Laboratories, ME). Bacteria were isolated from pooled fecal samples. Suspected isolates were confirmed by conventional biochemical assays, and those identified as Salmonella spp. were serotyped. A variation between seropositive percentages and positive fecal samples was observed. Serologically positive pigs decreased from S1 to S4, and subsequently increased from S4 to S7. The percentages of fecal positive culture increased from M1 to M3, and then declined in M4, increased in M5, and were negative in M6 and M7. In the study three serovars, Salmonella 3,10:e,h:-, Salmonella Muenster, and Salmonella Bovismorbificans, were identified with low pathogenicity for swine. Three multidrug resistance strains (one belonged to Salmonella 3,10:e,h:- and two belonged to Salmonella Muenster) were found. PFGE results showed three different but closely related patterns among the 13 isolates of Salmonella Bovismorbificans, and two patterns for the three Salmonella Muenster and Salmonella 3,10:e,h:- isolates. This longitudinal study established critical points of Salmonella spp. infection in the farm and the production stages, where appropriate control measures must be taken. PFGE showed clonal relationships in each serovar. Antibiotic resistance profiles should be periodically included due to public health concerns., Facultad de Ciencias Veterinarias

Pathological studies were carried out on the lungs of guinea pigs intratracheally inoculated with 4.6 × 106-8 colony forming units (CFU)/head of Actinobacillus pleuropneumoniae serovar 1. All animals in the highest dose group died within 24 hr post inoculation (hpi) and showed pulmonary lesions being hemorrhagic in nature while all animals in the lowest dose group were killed as scheduled at 11 days post inoculation (dpi) and showed only hyperplasia of peribronchial lymphoid tissues. In the middle dose group, two died within 24 hpi, two died at 9 dpi, and the remaining one was killed at 11 dpi. Two guinea pigs which died at 9 dpi showed fibrinonecrotic pleuropneumonia which is the most characteristic acute pulmonary lesion in swine, and has not yet been reproduced in laboratory animals up to the present time. This suggests that guinea pigs may be a useful laboratory animal for studying the pathogenesis of Actinobacillus pleuropneumoniae infection in swine., Facultad de Ciencias Veterinarias

We describe an outbreak of vomiting, wasting, and encephalomyelitis syndrome in piglets in Argentina, caused by porcine hemagglutinating encephalomyelitis coronavirus (PHE-CoV) infection. Diagnosis was made by epidemiologic factors, pathologic features, immunohistochemistry, reverse transcription-PCR, and genomic sequencing. This study documents PHE-CoV infection in South America., Facultad de Ciencias Veterinarias

The effects of aflatoxin B1 on the development of the immune response to oil-adjuvanted Bordetella bronchiseptica vaccine and on acquired resistance to bacterial challenge were studied in rabbits. The doses of aflatoxin used were insufficient to produce clinical intoxication. Rabbits were randomly assigned to three groups, each having six animals: control (T), vaccinated (V), and vaccinated plus aflatoxin (VA) at 0.05 mg/kg daily per os. Groups V and VA were vaccinated twice, and the three groups were subsequently challenged with virulent B. bronchiseptica. The average weight gain at weekly intervals was significantly reduced in group VA, and no statistically significant differences were found in the titers of agglutinating antibodies between groups V and VA. There were significant differences between groups V and VA in the extent and severity of the pneumonic process, group VA being most affected. Results indicated that agglutinating antibody titers were not related to the level of protection in the latter group. Other mechanisms, such as alveolar macrophage activity and cell-mediated immunity, were implicated in the impairment of the acquired resistance in rabbits subclinically intoxicated with aflatoxin.

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% neutral formalin. From 3,153 piglets examined, less than 1% 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. 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%. Dos 3.153 leitões examinados, menos que 1% 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.

Histochemical and lectinhistochemical examinations were carried out on nasal mucosa of pigs with or without respiratory diseases. As the results, both acid and neutral mucins coexisted in nasal mucosa of normal pigs while acid sialomucins were mainly observed in nasal mucosa of pigs infected with Bordetella bronchiseptica and/or Pasteurella multocida. Lectinhistochemistry revealed that the nasal epithelial cells of normal pigs were rich in N-acetylgalactosamine, fucose and N-acetyl-glucosamine residues which showed a tendency to disappear in porcine cytomegalovirus infection and to increase in atrophic rhinitis, respectively., Facultad de Ciencias Veterinarias

The objective of the present study was to determine the prevalence of Toxoplasma gondii antibodies from slaughter sows and from pigs raised at an indoor and an outdoor swine farm. Serum samples were obtained from 230 slaughter sows belonging to 83 farms distributed in 5 provinces. Blood samples were collected monthly from pigs of different ages from an intensive management indoor farm (farm 1). A cross-sectional study was carried-out from an outdoor farm (farm 2). All sera were tested for T. gondii antibodies by the modified agglutination test (MAT), using formalin-fixed tachyzoites as antigen. An antibody titer > or =1:25 was considered positive. Antibodies to T. gondii were detected in 87 (37.8%) of 230 sows sera. Distribution among provinces was: 37.1% from Santa Fe, 62.8% from Buenos Aires, 3.3% from San Luis, 58.7% from La Pampa and 24% from Cordoba. Four of 88 (4.5%) serum samples from farm 1 had antibodies to T. gondii and none of the negative pigs seroconverted. However, 45 of 112 samples from farm 2 were positive (40.2%) with the following distribution: sows 100%; nursery 40%; growers 13.8% and fatteners 20%. It is concluded that the prevalence of T.gondii antibodies among sows seems to be quite variable. T. gondii prevalence was related to the facilities and management of the farm.

Se estudiaron durante dos periodos (anos 1996 y 1998-99), la prevalencia, los hallazgos anatomopatologicos y las probables causas de la constrictura rectal en cerdos de una granja intensiva en confinamiento. En el primer periodo se realizaron 660 necropsias de las categorias recria II, Desarrollo y engorde, siendo de 7.5% la mediana porcentual mensual de la constrictura rectal como causa primaria de muerte. Se observaron valores superiores al 10% en los meses de verano para las tres categorias de cerdos, en septiembre para la categoria recria II y en diciembre para la categoria Desarrollo. En el segundo periodo se realizaron 879 necropsias de las categorias Desarrollo y engorde. El porcentaje de constrictura rectal fue de 10, 3% y el de prolapso rectal 7.7%. La edad media fue de 164.2±6. L y 115.8±4.2 dias, respectivamente. Los cerdos presentaron una marcada distension abdominal y pobre desarrollo. A la necropsia se remarco la distension del recto, colon espiroideo y ciego, generalmente asociado a la presencia de exudado serofibrinoso, tanto en el peritoneo como en el pericardio. La lesion se caracterizo por una estrechez de recto ubicada entre 2.5 y 5 cm en craneal del ano, variando su longitud entre 3 y 8 cm. Los estudios bacteriologicos fueron negativos para patogenos primarios del cerdo. Se realizaron 122 analisis de aflatoxinas y zearalenona y 36 de deoxinivalenol de las materias primas del alimento mediante una prueba de ELISA por competicion. Si bien en el estudio realizado no se consignaron valores altos de zearalenona en correspondencia con los meses de alta prevalencia de constrictura rectal, con excepcion del mes de marzo, lo constante, a lo largo del ano, fue su consumo, asociado o no, con dioxinivalenol. Se desconoce lo que ocurre en condiciones de campo, por lo que no se puede excluir que dicha micotoxina participe en la patogenesis de la constrictura rectal, si la consideramos como una secuela del prolapso rectal.

Fetal fluids of 738 stillborn piglets from three swine farms in Argentina were examined for antibodies to Toxoplasma gondii. Antibodies were detected in 15 samples at a 1 : 20 dilution in the indirect fluorescent antibody test and 10 samples were positive in the modified agglutination test (MAT) at a dilution of 1 : 25; four of these samples had a MAT titer of ≥ 1 : 100. This survey indicates a low rate of congenital T. gondii infection in stillborn pigs in Argentina.

In order to determine susceptibility to Serpulina hyodysenteriae infection four inbred strains of SPF mice(Balb/cAnN, Balb/J, C57BL/6J and C57BL/6N) were inoculated with a single intragastric dose of 107 to 108colony forming units ( CFU ) Serpulina hyodysenteriae DJ 70 strain ( S.h ). The criteria used to evaluate theinfection were shedding of bacteria, in faeces at 3, 5, and 7 days post-inoculation (d.p.i), CFU per gram ofcecum, cecal macroscopic changes and histopathological lesions at 14 d.p.i. According to the bacteriologicalcounts and the degree of macroscopic changes the C57BL/6J mice strain seemed to be the most susceptible.Globlet cell hyperplasia, mononuclear cell infiltration of lamina propria and inflammatory oedema ofsubmucosa membrane were the most remarkable changes. No correlation between the lesions and the degreeof macroscopic findings was observed. Histopathological changes found in mice were correlated with thosereported previously in this species, but they differed from those found in pigs. However, progressivebacteriological counts and gross changes of cecum appeared to be a good indicators of S.h infection inC57BL/6J mice and this strain may be a useful animal model in order to study the "in vivo" sensibility of S.h to different antibiotics and chemotherapeutic., Facultad de Ciencias Veterinarias