Descrevem-se os achados clínicos e patológicos da paratuberculose em uma criação intensiva de bovinos de leite no municí pio de Capela de Santana, RS. Os sinais clínicos foram observados em oito de um total de 345 bovinos, consistindo em diarréia crônica refratária aos tratamentos, emagrecimento progressivo e queda na produção de leite. As principais lesões macroscópicas, observadas nos oito animais necropsiados, incluíam intestino delgado com acentuado espessamento da parede e superfície mucosa de aspecto reticulado, semelhante às circunvoluções cerebrais, lesão essa perceptível, através da serosa. A luz intestinal estava preenchida com conteúdo fluido e de aspecto leitoso. Os vasos linfáticos do mesentério mostravam-se mais evidentes sendo que alguns tinham aspecto varicoso. Os linfonodos mesentéricos estavam aumentados de volume e, ao corte, fluía grande quantidade de líquido leitoso. Focos de mineralização foram observados na íntima das artérias, nas válvulas cardíacas e na serosa do rúmen. As principais lesões macroscópicas incluíam enterite, linfadenite e linfangite granulomatosa caracterizada por infiltrado inflamatório com macrófagos, células gigantes de Langhans que continham grande quantidade de bacilos álcool-ácido-resistentes. As lesões vasculares consistiam em degeneração e mineralização das túnicas í ntimas e média das artérias de grande calibre associada a proliferação de colágeno. Havia calcificação da serosa do rúmen atrofia hepatocelular difusa e hepatite granulomatosa multifocal. O M. avium subsp. paratuberculosis (Map) foi isolado em amostras de intestino e linfonodos de 8 vacas Holandesas (3,5%) com doença de Johne, dentre 229 amostras cultivadas provenientes de um rebanho leiteiro. Amostras inoculadas em HEYM com micobactina produziram colônias identificadas como Map, segundo as caracterí sticas fenotí picas próprias como: crescimento lento, coloração álcool-ácido-resistente (A.A.R.) e dependência a micobactina. O laboratório de Referência da OIE confirmou a amostra isolada. O M. avium subsp. paratuberculosis (Map) foi isolado em amostras de intestino e linfonodos de 8 vacas Holandesas (3,5%) com doença de Johne, dentre 229 amostras cultivadas provenientes de um rebanho leiteiro Amostras inoculadas em HEYM com micobactina produziram colônias identificadas como Map, segundo as caracterí sticas fenotí picas próprias como: crescimento lento, coloração álcool-ácido-resistente (A.A.R.) e dependência a micobactina. O laboratório de Referência da OIE confirmou a amostra isolada. Não houve isolamento do agente em 221 amostras intestinais quando processadas, após 2 anos de sua colheita. O teste de IDGA aplicado como “screening”, detectou 26 vacas (11,4%) positivas, dentre 228 animais testados e sacrificados em matadouro. O teste de ELISA adsorvido, utilizando o antí geno PPA-3 detectou 125 (39,8%) amostras positivas. O ELISA não adsorvido detectou mais 32 (10,1%) reagentes positivos, dentre os 314 bovinos testados. A prevalência da infecção causada pelo Map em 36 rebanhos leiteiros procedentes de 25 municí pios do Rio Grande do Sul foi estimada em 44,6% das 1316 amostras testadas. A infecção foi identificada em 35 (97,2%) dos 36 rebanhos testados e presentes em todos os municí pios incluí dos. A ocorrência da doença de Johne foi enfatizada, tanto a forma clí nica quanto a infecção subclí nica no Rio Grande do Sul, sugerindo a adoção de medidas de controle sejam aplicadas na proteção dos rebanhos leiteiros nacionais. / The clinical and pathological aspects of bovine paratuberculosis in a dairy herd in the county of Capela de Santana, Rio Grande do Sul, southern Brazil are described. Clinical signs in eight cows out 345 cattle included chronic diarrhea refractory to treatment, progressive emaciation and decreased milk production. Necropsy findings included severe and diffuse thickening of the mucosa of the small intestine with exaggerated reticular pattern, reflected in the serosal surface, similar to cerebral gyri. Intestinal loops were filled with whitish watery contents. The lymphatic vessels of the intestinal serosa and of the mesentery were thickened and tortuous. The mesenteric lymph nodes were enlarged and, on cut surface, there were oozing of milky fluid. Plaques of mineralization were evident in the intima of larger arteries, in the endocardium of the heart valves and in the ruminal serosa. There was also edema of abomasal folds and atrophy of caudate lobe of the liver. The main histopathological findings were granulomatous enteritis, lymphadenitis and lymphangitis. The inflammatory infiltrate was composed of macrophages, epithelioid cells and Langhan`s giant cells containing large numbers of acid-fast bacilli. Vascular lesions included degeneration, calcification and collagen proliferation of the intima and media of larger arteries. Other microscopic lesions included calcification of the ruminal serosa, diffuse hepatocellular atrophy and multifocal granulomatous hepatitis. M. avium subsp. paratuberculosis (Map) was isolated from intestines and lymph nodes samples obtained from 8 Holstein cows (3.5%) with Johne’s Disease among 229 inoculated samples from a unique dairy herd in Rio Grande do Sul State, South Brazil. Cultures on HEYM supplemented with mycobactin yielded colonies identified like Map by phenotypic properties: Slow growth, acid-fast stain and mycobactin dependency. OIE Reference Laboratory in Argentine confirmed the strain like Map. The attempts to isolate the agent from 221 intestinal samples processed after 2 years were unsuccessful. The AGIDT applied as a screening test detected 26 positive cows (11.4%) among 228 tested animals at slaughterhouse. The absorbed ELISA test using PPA-3 antigen detected 125 positive animals (39.8%) and 47 (14.9%) suspect samples among 314 animals tested. Nonabsorbed ELISA test detected more 32 (10.1%) positive animals and 18 (5.7%) suspect samples than absorbed ELISA test. The prevalence of infection caused by Map was estimated in 35 bovine dairy herds in Rio Grande do Sul State by absorbed ELISA using PPA-3 commercial antigen. The ELISA test identified 558 positive (44.6%) animals among 1316 samples tested. The infection was detected in 35 dairy herds (97.2%) among 36 tested and was present in all 25 countries performed. The infection by Map was disseminated in dairy herds in Rio Grande do Sul State. It’ s emphasized the occurrence of clinical and subclinical forms of Johne’ s disease in Rio Grande do Sul and should be necessity the adoption of control measures in the protection of National dairy herds.

Background: Crohn's disease is a chronic inflammatory disease of the intestine in humans, with no known cause. Johne's disease is a chronic intestinal disease of ruminants caused by Mycobacterium avium suhspecies paratuberculosis (MAP), and has some features similar to Crohn's disease. Although MAP has been purported to play an etiologic role in Crohn's disease, this causal link is still under debate. Objective: The overall aim of this project is to analyze MAP strains from different hosts (cattle, sheep and humans) and regions in North Dakota by biochemical and epidemiological methods, in order to better understand the pathogenesis and epidemiology of MAP strains and the relationship between MAP and Crohn's disease. The specific aims of this research are the following: Aim 1. Investigate the epidemiological evidence for MAP as a cause of Crohn's disease. Aim 2. Conduct a comparative causality study to investigate whether MAP or other enteric pathogens cause Crohn's disease. Aim 3. Evaluate the occurrence of MAP infections in cattle in North Dakota, 1995-2005. Aim 4. Analyze MAP strains from symptomatic and asymptomatic cattle. Aim 5. Investigate the biochemical variations of rapid and slow growing MAP strains. Aim 6. Evaluate MAP strains from low shedders and high shedders. Methods: MAP isolates were analyzed by biochemical methods of gas chromatography, high performance liquid chromatography and mass spectrometry. In addition, extensive literature review was performed to (1) determine the epidemiologic causal link between MAP and Crohn' s disease and (2) determine whether MAP or other enteric pathogens cause Crohn's disease. Results: Results from our study indicated the availablity of epidemiologic evidence supporting the causal role of MAP in Crohn's disease. It was also demonstrated that MAP is the most implicated organism in the etiology of Crohn's disease when compared to other infectious agents. Investigation of the occurrence of MAP infection in North Dakota showed an increase in number of MAP cases reported, with seasonal trends. Biochemical typing of MAP strains from symptomatic and asymptomatic cattle indicated that the symptoms status of isolates was significantly associated with mass spectra patterns and shedder status (p < 0.05). However, the association between symptoms status and HPLC and GC patterns was not significant (p > 0.05). Investigation of biochemical variations of rapid and slow growing MAP strains showed associations between the biochemical variability of MAP strains and their growth rate and presence of symptoms in the source cattle. Evaluation of MAP strains of different shedding characteristics by univariate logistic regression revealed that the shedder status of isolates was significantly associated with growth rate of isolates, symptom status, and source regions, but not with mass spectra patterns of isolates. Conclusion: Overall, this study strengthens the theories of strain sharing, intraspecies and interspecies transmission, and supports an association between MAP and Crohn's disease. In addition, the understanding of the biochemical variation among MAP isolates will help in the future design of diagnostics, therapeutics and vaccines for Johne's and Crohn's diseases. / North Dakota State University. Department of Chemistry and Biochemistry

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

No description available.

Made available in DSpace on 2016-04-28T20:18:25Z (GMT). No. of bitstreams: 1 ELISE MIYUKI YAMASAKI.pdf: 7116323 bytes, checksum: 0698deb473a21808a4e19ade2a6072b4 (MD5) Previous issue date: 2010-01-21 / The epidemic and clinic-pathological aspects of paratuberculois in a dairy cattle herd in the Rio Claro county, southern Rio de Janeiro region, are described. In the years 2006-2009, eight adult cows presented chronic-intermittent diarrhea, chronic weight loss and normal appetite. At necropsy, the subserosal lymphatics were proeminent and dilated, mesenteric nodes were enlarged, and intestinal mucosa was corrugated, thickened and of microgranular aspect. Especially, in duodenum, was observed polipoids lesions in mucosa surface. Histopathology revealed, from the duodenum to the rectum, severe and diffuse granulomatous inflammation of the lamina propria and submucosa, broadened and distorced villi, marked dilatation of the lymphatic vessels in their apex, lymphangioectasia and granulomatous lymphangitis in the submucosa. Ziehl-Neelsen stain revealed variable amounts of acid-fast bacilli in macrophages, Langhan s giant cells and freely in the musosa and submucosa of the small intestine and colon, and in lymphnodes. Lesions in the lamina propria, particularly in the jejun and ileum, in some animals, were severe hypertrophy; polipoids lesions observed in duodenum mucosa was markedly muscularis mucosa hipertrophy , intestinals and duodenal glands hiperplasia. Mycobacterium avium subsp. paratuberulosis was isolated by bacterial cultivation of samples from feces, intestinal mucosa and milk, and identified through IS900 PCR. From 298 cows, older than three years, the percentage of reactive animals was 40%, in indirect ELISA test. The diagnosis of paratuberculosis was based on clinic-epidemiological data, sorology, bacterial isolation and IS900 PCR. After the adoption of control measures, as slaughter of sick cows and selective slaughter of soropositive animals, was observed reduction of clinical cases in the herd, from six cases to one case per year, in three years of study. / Descreve-se os aspectos epidemiol?gicos e cl?nico-patol?gicos da paratuberculose em um rebanho bovino leiteiro no munic?pio de Rio Claro, regi?o Sul-Fluminense, Rio de Janeiro. No per?odo de 2006 a 2009, oito vacas adultas da ra?a Girolanda apresentaram diarreia cr?nico-intermitente, perda de peso progressivo e apetite normal. ? necropsia observou-se vasos linf?ticos subserosos proeminentes, linfonodos mesent?ricos aumentados de volume, ?midos ao corte, serosa do intestino com aspecto anelado e cerebr?ide, mucosa espessada, pregueada e com aspecto microgranular. Em especial, no duodeno havia les?es polip?ides na supef?cie da mucosa. ? microscopia, desde o duodeno at? o intestino grosso, havia acentuada inflama??o granulomatosa difusa, marcada dilata??o dos vasos linf?ticos no ?pice das vilosidades, linfangiectasia e linfangite granulomatosa na submucosa, muscular e serosa, altera??es tamb?m vistas nos linfonodos mesent?ricos. A colora??o de Ziehl-Neelsen revelou, vari?vel quantidade de bacilos ?lcool-?cido resistentes no interior de macr?fagos, c?lulas gigantes de Langhans e livres na mucosa e submucosa do intestino delgado e grosso e em linfonodos mesent?ricos. A l?mina pr?pria da mucosa, principalmente do jejuno e ?leo de alguns animais, apresentava acentuada hipertrofia; as les?es polip?ides correspondiam ? marcada hipertrofia da muscular da mucosa, hiperplasia de gl?ndulas duodenais e intestinais. Mycobacterium avium subsp. paratuberculosis foi isolado em cultivo bacteriano a partir de amostras de fezes, raspado de mucosa intestinal e leite e identificado pela t?cnica de PCR IS900. Atrav?s da avalia??o sorol?gica semestral, foram analisadas 298 vacas, a partir de tr?s anos de idade, e observou-se cerca de 40% de animais reagentes ao teste ELISA indireto no per?odo estudado. O diagn?stico da paratuberculose foi baseado nos dados cl?nicopatol?gicos, sorologia, isolamento e identifica??o do agente em amostras de fezes, raspado de mucosa e leite, atrav?s do cultivo bacteriano e PCR IS900. Ap?s implementa??o de medidas de controle, tais como elimina??o de animais doentes, abate seletivo dos soropositivos, separa??o dos bezerros ao nascer com utiliza??o de banco de colostro, observou-se diminui??o da ocorr?ncia de casos cl?nicos no rebanho, de seis casos por ano para cerca de um caso por ano, em tr?s anos de estudo.

Made available in DSpace on 2015-03-26T13:47:19Z (GMT). No. of bitstreams: 1 texto completo.pdf: 709722 bytes, checksum: 25ae10b4477351d0ee2293c5f5d08d05 (MD5) Previous issue date: 2012-04-27 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Mycobacterium avium subspecies paratuberculosis (MAP) is the etiological agent of paratuberculosis, a disease which causes chronic granulomatous enteritis preferably in domestic and wild ruminants. It is characterized by intermittent diarrhea, progressive weight loss and reduced milk production. The major route of transmission is the ingestion of food and water contaminated by feces of infected animals. It is considered a disease of high economic importance, because of losses in livestock and importance in human health, since there is evidence of possible correlation of MAP with Crohn's disease. Although previous researches have contributed to advances in the diagnosis of subclinical MAP in animals, there is a lack of studies concerning the correct understanding of its pathophysiology. Thus, the aim of this study was to investigate the distribution of MAP by means of the histology and nested-PCR techniques in organs of C57BL/6 mice infected with MAP66115-98 strain at a dose of 3 x 108 CFU /mL intraperitoneally (IP). It was applied 250&#956;l of inoculum in 20 mice, and it was applied saline phosphate buffer (PBS) in eight control species. The animals were euthanized at 30, 60, 90 and 120 days post-inoculation, and fragments of spleen, liver, colon, ileum and Peyer's patches of five mice and two control, for each period of time, were performed molecular and histopathological evaluations. Although it was not found histologic lesions in sections stained by Hematoxylin Eosin, there was a positive staining for two Peyer s patches referring to 90 and 120 days after inoculation, stained by Ziehl-Neelsen. Among the collected organs, 64.9% were positive by molecular technique. The spleen (0.85), colon (0.75) and liver (0.60) had the highest proportion of positive regardless of the evaluation period. Taking into consideration the time after inoculation, the spleen had a higher proportion of positive results after 60 days of infection (1.00), remaining stable until 120 days. The colon had a higher proportion at 30 days (1.00) and drastically reduced to 90 days (0.40). The liver ranged between 0.40 and 0.80 during the four periods of evaluation and the Ileum showed positivity ratio equal to 0.80 only at 120 days of infection. Moreover, Peyer's patches did not vary significantly (0.40) from day 60, remaining with the lowest ratio among the organs studied. The assessment of the probability of infection of an organ relative to another was obtained by the Relative Risk, where the highest values were observed in the ratio of spleen/Peyer's patches (2.00), colon/Peyer's patches (1.74), spleen/ileum (1.54) and spleen/liver (1.40). The highest odds ratio values were observed in the spleen/Peyer s patches (7.56), spleen/ileum (4.64), spleen/liver (3.78), and colon/ileum (2.45). However, among all the established associations, only the relations spleen / ileum and spleen / Peyer's patches were statistically significant at the level of 95%, showing that the spleen was the organ with higher risk and chances of positivity in relation to the ileum and Peyer's patches. Thus, these results can contribute to better understanding of the distribution of MAP in experimental models during the course of systemic infection, being this the first study to correlate the infective capacity of the strain MAP66115- 98 in C57BL/6 mice with a distribution in different organs after inoculation by intraperitoneal route. / Mycobacterium avium subespécie paratuberculosis (MAP) é o agente etiológico da paratuberculose, uma enfermidade que causa enterite granulomatosa crônica preferencialmente em ruminantes domésticos e silvestres. É considerada uma doença de impacto na economia, devido às perdas no rebanho e na saúde humana, uma vez que se têm indícios da possível relação de MAP com a doença de Crohn. Embora pesquisas tenham contribuído para avanços no diagnóstico de MAP, há carências de estudos relacionados à compreensão de sua patofisiologia. Desse modo, este estudo propôs avaliar a distribuição de MAP por meios das técnicas de nested-PCR e histologia em órgãos de camundongos C57BL/6 infectados por via intraperitoneal com a cepa MAP66115-98. Em 20 camundongos foram aplicados 250&#956;l de inóculo contendo 3 x 108 UFC/mL e, em oito controles foram aplicados tampão fosfato-salina (PBS). Os animais foram eutanasiados aos 30, 60, 90 e 120 dias pós-inoculação. Em cada período, foram coletados baço, fígado, cólon, íleo e placas de Peyer de cinco camundongos desafiados e dois controles. O material foi dividido para avaliação molecular e histopatológica. Embora não tenham sido verificadas alterações histológicas nas lâminas coradas pela Hematoxilina Eosina, houve marcação positiva para duas placas de Peyer, referentes a 90 e 120 dias pós-inoculação, quando coradas pela técnica de Ziehl-Neelsen. Dentre os órgãos coletados, 64,9% foram positivos pela técnica molecular. Os órgãos que apresentaram maiores valores proporcionais de positividade independentemente do período de avaliação foram o baço (0,85), o cólon (0,75) e o fígado (0,60). Ao levar em consideração o tempo pós-inoculação, o baço apresentou maior proporção de positividade após 60 dias (1,00), permanecendo estável até os 120 dias, enquanto o cólon apresentou maior proporção aos 30 dias (1,00) e reduziu drasticamente aos 90 dias (0,40) da inoculação. O fígado variou entre 0,40 e 0,80 durante os quatro períodos de avaliação e o Íleo apresentou proporção de positividade igual a 0,80 apenas aos 120 dias de inoculação. Por outro lado, as placas de Peyer não variaram significativamente a partir dos 60 dias (0,40) permanecendo com a menor proporção dentre os órgãos analisados. A avaliação da probabilidade de infecção de um órgão em relação a outro foi obtida pelo Risco Relativo, onde os maiores valores foram verificados na relação entre baço/placas de Peyer (2,00); cólon/placas de Peyer (1,74); baço/íleo (1,54) e baço/fígado (1,40). Os maiores valores de Razão de Chances foram verificados na relação entre baço/placas de Peyer (7,56); baço/íleo (4,64); baço/fígado (3,78) e cólon/íleo (2,45). Contudo, dentre todas as associações estabelecidas, apenas as relações: baço/íleo e baço/placas de Peyer foram estatisticamente significativas à nível de 95%, demonstrando que o baço foi o órgão com maior risco e chances de positividade em relação ao íleo e placas de Peyer. Assim, estes resultados podem contribuir para a melhor compreensão da distribuição de MAP em modelos experimentais durante o curso de uma infecção sistêmica, sendo o primeiro trabalho a correlacionar a capacidade infectiva da cepa MAP66115-98 nos camundongos C57BL/6 com a sua distribuição em diferentes órgãos pós-inoculação usando a via intraperitoneal.

Mycobacterium avium ssp. paratuberculosis (Map), agent étiologique de la paratuberculose, a évolué en deuxtypes dénommés, S pour« Sheep » et C pour « Cattle ». L’intestin grêle est le site primaire de l’infection à Map mais les mécanismes moléculaires impliqués dans l’implantation du bacille restent largement méconnus. L’objectif de mon projet de thèse visait à identifier et caractériser les adhésines exprimées par Map par des approches génétiques et biochimiques. J’ai ainsi purifié la HBHA et la LBP par chromatographie d’affinité puis les ai identifiés en spectrométrie de masse. L’originalité de ce travail repose sur le polymorphisme de ces adhésines observé entre les souches de type C et S. Cette variabilité a été mise en évidence sur le domaine d’interaction avec les sucres sulfatés de la cellule hôte influençant l’affinité des adhésines pour l’héparine. Ce travail de thèse a permis de caractériser pour la première fois ces deux adhésines produites par Map. Le polymorphisme de la HBHA et de la LBP, discriminant les types C et S, ouvre de nombreuses perspectives sur l’évolution de l’espèce M. avium et le rôle de ces adhésines sur le tropisme intestinal, la préférence d’hôte de Map ou encore leur potentiel diagnostic. / Mycobacterium avium subsp. paratuberculosis (Map), the etiological agent of paratuberculosis, has evolved into two types called, S for "Sheep" and C for "Cattle." The small intestine is the primary site of Map infection but the molecular mechanisms involved in the establishment of bacilli are still unknown. The aim of my thesis was to identify and characterize the adhesins expressed by Map by genetic and biochemical approaches. I purified HBHA and LBP by affinity chromatography then identified them by mass spectrometry. The originality of this work is based on the polymorphism of these adhesins observed between strains of type C and S. This variability has been demonstrated in the binding domain involved in interaction with sulfated sugars of host cell influences adhesins affinity for heparin. This thesis has characterized for the first time these two adhesins produced by Map. Specific polymorphism highlighted related to the evolution of the species avium, opens large number questions on their role on the pathogenesis of Map including the cellular tropism, host preference or interest of these antigens to improve diagnostic.

No description available.

La paratuberculose est une maladie entérique incurable causée par la bactérie Mycobacterium avium subsp. paratuberculosis (MAP) endémique dans la plupart des régions du monde. Cette affection ciblant les ruminants est responsable d’importantes pertes économiques dans les productions animales et son contrôle est particulièrement difficile. L’ingestion de matières contaminées (fèces, lait et colostrum) est considérée comme la voie principale de transmission. La situation épidémiologique de la paratuberculose dans les troupeaux ovins du Québec demeure inconnue. Ce projet visait à évaluer la prévalence de MAP et à caractériser les facteurs de risque associés aux statuts positifs des ovins du Québec. Au total, 2942 brebis provenant de 70 fermes ovines, dont 10 productions laitières et 60 productions de boucherie, ont été échantillonnées dans le cadre de ce projet entre février 2020 et mars 2022. La prévalence réelle des moutons positifs dans la province a été estimée à 8.3% (IC 95% 4.7-14.1%) alors que la prévalence apparente de troupeaux positifs a été estimée à 29.9% (IC 95% 25.7-34.1%). L’analyse multivariée des facteurs de risque a permis d’identifier la présence de signes cliniques comme facteur de risque à un statut positif individuel (RC = 3.0; IC 95% 1.3-7.4) et l’utilisation d’un logiciel de régie pour les données de santé des animaux comme un facteur protecteur à un statut de troupeau positif (RC = 0.1; IC 95% 0.0-0.6). Les résultats de cette étude permettront l’exploration de mesures de contrôle de l’infection dans les troupeaux ovins de la province. / Paratuberculosis is an incurable enteric disease caused by Mycobacterium avium subsp. paratuberculosis (MAP), which is endemic in most parts of the world. This disease affecting ruminants is responsible for significant economic losses in livestock production and is particularly difficult to control. Ingestion of contaminated material (e.g., faeces, milk, colostrum) is considered the main route of transmission of MAP. The epidemiological situation of paratuberculosis in Quebec sheep flocks remains unknown. Hence, the purpose of this project was to evaluate the prevalence of MAP as well as to characterize the risk factors associated with positive status within Quebec sheep. A total of 2942 ewes from 70 sheep farms, including 10 dairy and 60 meat farms, were sampled between March 2020 and March 2022. The true prevalence of positive sheep in the province was estimated at 8.3% (IC 95% 4.7-14.1%) while the apparent prevalence of positive flocks was estimated at 29.9% (95% IC 25.7-34.1%). Multivariable analysis of risk factors identified the presence of clinical signs as risk factor for a positive ewe status (OR = 3.0; 95% CI 1.3-7.4) and the use of animal health data management software as a protective factor for positive flock status (OR = 0.1; 95% CI 0.0-0.6). The results of this study will enable the implementation of MAP-tailored infection control measures in the province's sheep flocks.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.