Severity of bovine tuberculosis is associated with co-infection with common pathogens in wild boar

Co-infections with parasites or viruses drive tuberculosis dynamics in humans, but little is known about their effects in other non-human hosts. This work aims to investigate the relationship between Mycobacterium bovis infection and other pathogens in wild boar (Sus scrofa), a recognized reservoir of bovine tuberculosis (bTB) in Mediterranean ecosystems. For this purpose, it has been assessed whether contacts with common concomitant pathogens are associated with the development of severe bTB lesions in 165 wild boar from mid-western Spain. The presence of bTB lesions affecting only one anatomic location (cervical lymph nodes), or more severe patterns affecting more than one location (mainly cervical lymph nodes and lungs), was assessed in infected animals. In addition, the existence of contacts with other pathogens such as porcine circovirus type 2 (PCV2), Aujeszky's disease virus (ADV), swine influenza virus, porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Haemophilus parasuis and Metastrongylus spp, was evaluated by means of serological, microbiological and parasitological techniques. The existence of contacts with a structured community of pathogens in wild boar infected by M. bovis was statistically investigated by null models. Association between this community of pathogens and bTB severity was examined using a Partial Least Squares regression approach. Results showed that adult wild boar infected by M. bovis had contacted with some specific, non-random pathogen combinations. Contact with PCV2, ADV and infection by Metastrongylus spp, was positively correlated to tuberculosis severity. Therefore, measures against these concomitant pathogens such as vaccination or deworming, might be useful in tuberculosis control programmes in the wild boar. However, given the unexpected consequences of altering any community of organisms, further research should evaluate the impact of such measures under controlled conditions. Furthermore, more research including other important pathogens, such as gastro-intestinal nematodes, will be necessary to complete this picture

COINFECCIÓN DE CIRCOVIRUS PORCINO TIPO 2 CON EL VIRUS DEL SÍNDROME RESPIRATORIO Y REPRODUCTIVO PORCINO EN VENEZUELA

El circovirus porcino tipo 2 (PCV2) que ha sido asociado al síndrome de emaciación multisistémico postdestete (PMWS), generalmente es diagnosticado conjuntamente con otros agentes infecciosos en cerdos. El virus del síndrome respiratorio y reproductivo porcino (PRRSV) es probablemente el más frecuentemente asociado a estos casos. Aunado a ello, se ha sugerido una potencial relación entre ambos agentes, basándose en infecciones experimentales. Tomando en cuenta que ambos virus, PRRSV y PCV2, han sido detectados en Venezuela, es posible que la coinfección por estos agentes ocurra de forma natural bajo condiciones de campo en el país; en razón de lo cual, el objetivo del presente trabajo fue describir los signos clínicos, las lesiones macroscópicas y microscópicas, así como la detección de ambos virus en cerdos naturalmente coinfectados en Venezuela. Entre noviembre del 2001 y noviembre del 2002, fueron estudiados 27 cerdos entre 6 y 12 semanas de edad, provenientes de 11 granjas, las cuales presentaron capacidades entre 300 y 1.500 madres, estando ubicadas en los estados Aragua, Carabobo, Cojedes, Mérida, Yaracuy y Zulia. Los signos clínicos y las lesiones macro y microscópicas de los cerdos seleccionados fueron registradas. Muestras de tonsila, pulmón, nódulos linfáticos, bazo, hígado, intestino y riñón, fueron fijadas en formalina bufferada al 10% para la realización del examen histopatológico. Los casos compatibles con PMWS fueron procesados según la técnica de hibridación in situ (HIS) para detectar PCV2, realizándose inmunohistoquímica (IHQ) para PRRSV a las muestras positivas a PCV2, de manera de detectar aquellos casos de co–infección viral. De los 27 cerdos con signos clínicos como retraso en el crecimiento y disnea, 10 evidenciaron lesiones microscópicas consistentes con PMWS, de estos últimos, cinco resultaron positivos a la prueba de HIS, tres de ellos (dos con PMWS y uno con infección subclínica de PCV2) se encontraron positivos a PRRSV mediante la prueba de IHQ, siempre con identificación del agente en macrófagos alveolares.Coinfection of Porcine Circovirus Type 2 with Porcine Reproductive and Respiratory Syndrome virus in VenezuelaABSTRACTPorcine circovirus type 2 (PCV2) is usually found concomitantly with other agents in postweaning multisystemic wasting syndrome (PMWS). Among them, porcine reproductive and respiratory syndrome virus (PRRSV) is probably the most frequent one. Furthermore, a potential synergy between those agents has been suggested based on experimental infections. Taking into account that both PRRSV and PCV2 have been detected in Venezuela, it is possible that coinfections by these viral agents occur under field conditions. Therefore, the purpose of this work was to describe the clinical signs, gross lesions observed, histopathological findings and detection of both PCV2 and PRRSV in pigs naturally co-infected with these viruses in Venezuela. Between november 2001 and november 2002, twenty seven 6-12 weekold pigs, taken from eleven farms with 300 to 1500 sows were studied. Herds were located in the states of Aragua, Carabobo, Cojedes, Mérida, Yaracuy and Zulia. Clinical signs and macroscopic lesions of selected pigs were registered. Samples of tonsil, lung, lymph nodes, spleen, liver, intestine and kidney were fixed by immersion in 10% buffered formalin for histopathological examination. Those cases compatibles with PMWS were further processed by in situ hybridization (ISH) to detect PCV2. Finally immunohystochemestry (IHC) for PRRSV detection was only performed in the PCV2 positives samples in order to detect those cases of viral co-infection. Ten out of 27 pigs with clinical signs, growth retardation and respiratory signs, showed microscopic lesions compatible with those of PMWS, five out of these last 10 were positive to ISH to detect PCV2. IHC to detect PRRSV antigen was performed in those 5 PCV2 positive cases. Three of them (two with PMWS and the third with a PCV2 subclinical infection) were found positive to the PRRSV IHC test; labeled cells consisted of alveolar macrophages

PRIMER REPORTE EN VENEZUELA DEL SÍNDROME DE EMACIACIÓN MULTISISTÉMICO POST-DESTETE PORCINO

En años recientes el Síndrome Multisistémico de Emaciación Post Destete Porcino (PMWS) ha tenido importancia en la industria porcina en muchos países, particularmente en Canadá, Europa, Estados Unidos de América, Asia y Sur América. El síndrome afecta cerdos jóvenes, principalmente entre 6 y 14 semanas de edad. El PMWS está caracterizado por emaciación, neumonía, diarrea, ictericia y aumento de volumen de los linfonódulos. El síndrome ha sido asociado con un circovirus porcino tipo 2 (PCV2) y, simultáneamente pueden ocurrir otras enfermedades: parvovirus porcino, virus del síndrome respiratorio y reproductivo porcino (PRRS), etc. El diagnóstico del PMWS se basa en la edad de los cerdos afectados, la típica apariencia de emaciación, hallazgos de necropsia, histopatológicos, y exámenes de Hibridación in situ (HIS) en tejidos que revelan la presencia de PCV2. El presente estudio se realizó en 12 lechones de 8 a 12 semanas de edad, ubicados en 3 granjas porcinas de estados centrales de Venezuela (Aragua/Carabobo). Los lechones presentaban signos de consunción, palidez generalizada, disnea, diarrea e hipertrofia de linfonódulos superficiales inguinales. A la necropsia se evidenció neumonía con pulmones no colapsables e incremento de tamaño de linfonódulos inguinales, mesentéricos y traqueobronquiales; mientras en la histopatología se evidenció depleción linfoide con pérdida de la arquitectura folicular en linfonódulos, bazo y placas de Peyer, con presencia de infiltración histiocitaria, células sincitiales y corpúsculos intensamente basófilos intracitoplasmáticos en histiocitos, lo cual es altamente sugestivo de PMWS. Adicionalmente se procesaron muestras de estos mismos tejidos mediante una técnica de HIS, que permitió demostrar la presencia de PCV2 en los tejidos linfoides afectados y confirmar el diagnóstico de PMWS. Esta es la primera descripción de esta entidad patologica en Venezuela.Postweaning Multisystemic Wasting Swine Syndrome, First Report in VenezuelaAbstractIn recent years Post Weaning Multisystemic Wasting Syndrome has become of significant concern in the swine industry in many countries, particularly Canada, United States of America, Europe, Asia and South America. The syndrome affects pigs mainly between 6 and 14 weeks of age. It is characterized by wasting, pneumonia, diarrhea, jaundice and enlarged lymph nodes. The syndrome has been associated with a porcine circovirus type 2 (PCV2) and simultaneous infections with porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus (PRRS) etc. The diagnosis of PMWS syndrome is based on the age of affected pigs, typical wasting appearance and necropsy lesions, histopathologic study and in situ hybridization (ISH) of affected tissues, showing the presence of PCV2 by HIS methods. The present study was performed in 12 piglets between 8 and 12 weeks of age, located in 3 porcine farms from Central States of Venezuelan (Aragua/Carabobo). The pigs showed signs of comsumption, pallor, dispnea, diarrhea, and enlarged superficial inguinal lymph nodes. At necropsy there was evidence of pneumonia with noncolapsable lungs as well as inguinal, mesenteric and tracheobronchial lymph nodes enlargement The histopathology study showed lymphoid depletion, with loss of follicles architecture in lymph nodes, spleen, and Peyer´s patches, histiocytic infiltration, sincitial cells and basophilic cytoplasmic inclussions in histiocytic cells. The findings described are suggestive of PMWS. The same tissues specimen were processed by a technique of IHS and revealed the presence of PCV2 in the affected lymphoid tissues to confirm the diagnosis of PMWS. This is the first description of the syndrome in Venezuela

Brief description of main clinical signs and lesions produced by the respiratory pathogens assessed. The type of assay carried out to diagnose them is also shown.

<p>Brief description of main clinical signs and lesions produced by the respiratory pathogens assessed. The type of assay carried out to diagnose them is also shown.</p

Percentage of animals positive against the selected respiratory pathogens included in this study in 24 juveniles (6–12 months), 45 yearlings (13–24 months) and 96 adult (over 24 months) wild boar hunter harvested in mid-western Spain.

<p>Percentage of animals positive against the selected respiratory pathogens included in this study in 24 juveniles (6–12 months), 45 yearlings (13–24 months) and 96 adult (over 24 months) wild boar hunter harvested in mid-western Spain.</p

Predictor weights of the Partial Least Squares regression (PLSr) model explaining the effects of presence of antibodies elicited by porcine circovirus type 2 (PCV2), Aujeszky's disease virus (ADV), swine influenza virus (SIV), <i>Mycoplasma hyopneumoniae</i> and co-infection by <i>Metastrongylus</i> lung nematodes on bTB severity.

<p>Predictor weights represent the contribution of each pathogen infection to the PLSr's × axis. Predictor weights explaining more than 10% of the total variance in each response variable are shown in bold type. The exposure to porcine reproductive and respiratory syndrome virus (PRRSV), <i>Haemophilus parasuis</i>, and <i>Actinobacillus pleuropneumoniae</i> were excluded from this analysis since their prevalence in studied wild boar population was lower than 5% (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110123#pone-0110123-t002" target="_blank">table 2</a>).</p><p>Predictor weights of the Partial Least Squares regression (PLSr) model explaining the effects of presence of antibodies elicited by porcine circovirus type 2 (PCV2), Aujeszky's disease virus (ADV), swine influenza virus (SIV), <i>Mycoplasma hyopneumoniae</i> and co-infection by <i>Metastrongylus</i> lung nematodes on bTB severity.</p

Observed frequencies for different pathogen assemblages (%) including <i>Metastrongylus</i> spp and <i>Mycobacterium bovis</i> infection and, <i>Mycoplasma hyopneumoniae</i> (Mhyo), Porcine circovirus type 2 (PCV2), Swine influenza virus (SIV), and Aujeszky's disease virus (ADV) antibodies positivity in 165 adult, yearling and juvenile males and females wild boar hunter-harvested in mid-western Spain.

<p>Zero indicates lack of detectable antibodies or pathogen whereas 1 indicates presence of antibodies against the specific pathogen. For <i>Metastrongylus</i> spp and <i>M. bovis</i>, 1 indicates presence of the pathogen in the corresponding samples. In bold, some specific combinations that appeared in more than 5% of studied boars.</p><p>Observed frequencies for different pathogen assemblages (%) including <i>Metastrongylus</i> spp and <i>Mycobacterium bovis</i> infection and, <i>Mycoplasma hyopneumoniae</i> (Mhyo), Porcine circovirus type 2 (PCV2), Swine influenza virus (SIV), and Aujeszky's disease virus (ADV) antibodies positivity in 165 adult, yearling and juvenile males and females wild boar hunter-harvested in mid-western Spain.</p

The study area is located in mid-western Spain where wild boar is the most important reservoir of bovine tuberculosis.

<p>The study area is located in mid-western Spain where wild boar is the most important reservoir of bovine tuberculosis.</p

Wild boar showing localized (bTB like lesion in submandibular lymph node) (a) or generalized bTB lesion patterns (bTB like lesions in lungs) (b).

<p>Wild boar showing localized (bTB like lesion in submandibular lymph node) (a) or generalized bTB lesion patterns (bTB like lesions in lungs) (b).</p