Dynamic of excretion and immune response of experimentally infected pigs with monophasic varient of Salmontella typhimurium serovar 1,4[5], 12:i:-

In recent years Salmonella enterica serovar Typhimurium 1,4[5],12:i:- (mono-phasic variant of S. Typhimurium or vmST) was focused as a major zoonotic problem because produce human gastroenteritis outbreaks in many countries. Human disease caused by this serovar is considered as emergent in European Union countries and actually is ranked as the third most reported serotype after S. Enteritidis and S. Typhimurium (EFSA, 2016; Fernandes et al., 2016)

Coinfections and their molecular consequences in the porcine respiratory tract

Understudied, coinfections are more frequent in pig farms than single infections. In pigs, the term “Porcine Respiratory Disease Complex” (PRDC) is often used to describe coinfections involving viruses such as swine Influenza A Virus (swIAV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), and Porcine CircoVirus type 2 (PCV2) as well as bacteria like Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae and Bordetella bronchiseptica. The clinical outcome of the various coinfection or superinfection situations is usually assessed in the studies while in most of cases there is no clear elucidation of the fine mechanisms shaping the complex interactions occurring between microorganisms. In this comprehensive review, we aimed at identifying the studies dealing with coinfections or superinfections in the pig respiratory tract and at presenting the interactions between pathogens and, when possible, the mechanisms controlling them. Coinfections and superinfections involving viruses and bacteria were considered while research articles including protozoan and fungi were excluded. We discuss the main limitations complicating the interpretation of coinfection/superinfection studies, and the high potential perspectives in this fascinating research field, which is expecting to gain more and more interest in the next years for the obvious benefit of animal health

Épidémiologie de la pathologie pulmonaire chez le porc en croissance (identification de facteurs de risque et perspectives pour la prévention)

Les maladies pulmonaires constituent de par le monde un problème majeur de santé chez le porc en croissance élevé dans des conditions confinées et selon un mode intensif. La pneumonie et la pleurésie représentent les deux affections pulmonaires les plus fréquentes. La recherche de moyens de prévention nécessite une connaissance approfondie de leur épidémiologie. L'objectif de cette thèse est d'identifier les facteurs associés à la pneumonie et à la pleurésie. Afin de s'assurer de la validité des méthodes à adopter pour évaluer le statu d'infection des animaux vivants par des pathogènes respiratoires ainsi que des catégories d'animaux à prélever, ceux études observationnelles préliminaires on été menées. Une enquête analytique a ensuite été réalisée pour identifier les déterminants de la pneumonie et de la pleurésie. Le rôle des facteurs infectieux et non infectieux dans explication de ces deux maladies a été mise en évidence. Mycoplasma hyopneumoniae et le sous H1N1 des virus influenza porcins jouent un rôle majeur dans l'explication de la pneumonie tandis qu'Actinobacillus pleuropneumoniae constitue l'agent central de la pleurésie. Le virus du syndrome dysgénésique et respiratoire porcin intervient dans le développement et la sévérité d'atteinte à l'égard des deux maladies. Des facteurs ayant trait à la conduite et aux pratiques d'élevage, à l'hygiène et aux conditions de logement du porc ont été mises en évidence comme éléments associés à la pneumonie et à la pleurésie. En regard des résultats obtenus, des mesures de maîtrise et de prévention des maladies pulmonaires peuvent être proposées.Respiratory diseases are a major health issue for pigs reared under confined conditions in intensive systems worldwide. Pneumonia and pleuritis are the two most frequent lung alterations. The aetiology of these diseases is complex and multifactorial. A better knowledge of the epidemiology of lung diseases is needed to implement adequate control strategies. The aim of the present work is to identify herd-factors associated with lung diseases, particularly pneumonia and pleuritis in slaughtered pigs from farrow-to-finish farms. Two preliminary observational studies were carried out to assess the relevance of different sampling methods to determine the infectious status of the pigs and to identify the category of pigs which must be sampled in a further analytical study. In a second step, a cross-sectional study was carried out in 143 herds to identify the risk factors for pneumonia and pleuritis. Infectious and noninfectious factors were founded to be associated with lung diseases. Mycoplasma hyopneumoniae, H1N1 subtype of swine influenza viruses are the major pathogens involved in pneumonia whereas Actinobacillus pleuropneumoniae is the main agent associated with pleuritis. Porcine respiratory and reproductive syndrome virus acts on both types of lung lesions. Noninfectious factors related to management and husbandry practices, hygiene and housing conditions are also involved in pneumonia and pleuritis. All these results would be helpful to define appropriate herd health management programmes targeting the reduction of respiratory disease incidence.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

ACPVI multibloc qualitative. Application en épidémiologie vétérinaire.

International audienceUne nouvelle présentation de l'Analyse en Composantes Principales sur Variables Instrumentales Multibloc, dont l'objectif est de prédire un tableau Y à partir de plusieurs tableaux (X1, ..., XK), est proposée. Elle est basée sur la détermination, pas à pas, de composantes dans l'espace des variables Y. Chaque composante est projetée sur les espaces engendrés respectivement par les variables des tableaux Xk (k=1, ..., K). L'ACPVI multibloc consiste à maximiser, en moyenne, la variance restituée par ces projections. Cette méthode multibloc est ensuite appliquée au cadre de la description et la prédiction d'une variable qualitative y par un ensemble de variables qualitatives (x1, ..., xK), chaque variable étant codée en un tableau contenant les indicatrices de ses modalités. La discrimination est opérée sur la base de composantes globales mutuellement orthogonales résumant l'ensemble des variables explicatives. La démarche d'analyse est comparée à d'autres méthodes de discrimination qualitative et illustrée sur la base d'une étude de cas en épidémiologie vétérinaire

The Positioning Of Organic Pig Farms In The Landscape Of Alternative Pig Production In France

A survey was made in organic and other pig farms alternative to indoor housing on fully slatted floor with the aim of describing the different housing systems and of identifying the pig health problems, the possible improvements in animal welfare and biosecurity levels. The answers from 102 questionnaires were analysed with multiple correspondence analyses followed by hierarchical clusterings. Three main types of systems were identified: farms close to conventional farms as regard to the housing premises, farms mainly under the French ‘Label Rouge Fermier’ and with part of their pigs raised outdoors and farms mainly organic, characterized by runners allowing outdoor access (sows, gilts, fattening pigs) and litter bedding for indoor compartments (farrowing sows and weaners) and by more frequent reproduction disorders in sows and a lack of sanitary lock. Our study confirmed a diversity in alternative housing systems but a relative homogeneity in organic systems in the study sample

Pig Farming in Alternative Systems: Strengths and Challenges in Terms of Animal Welfare, Biosecurity, Animal Health and Pork Safety

International audienceIn pig production, the widespread conventional indoor system with a slatted floor currently dominates. However, this production system is becoming less socially acceptable. In addition to general environmental protection issues, animal welfare, the absence of suffering and distress, and the management of pain also constitute societal concerns. In this context, alternative production systems are gaining ground. Although they are popular with consumers and other citizens, these alternative systems have their critical points. Here, we reviewed the international scientific literature to establish the state of the art of current knowledge regarding welfare, biosecurity, animal health and pork safety in this type of farming system. In general, alternative farms give pigs the opportunity to express a broader range of behaviours than conventional farms. However, the management of feeding, watering, temperature and predators is often more complicated in these outdoor systems. In addition, biosecurity measures seem to be applied less strictly in alternative farms than in conventional farms, especially in free-range systems, where they are more difficult to implement. On the other hand, pigs kept in these farming systems seem to be less affected by respiratory diseases, but parasitism and piglet crushing (in farrowing units) both remain a real challenge. Furthermore, the higher prevalence of many zoonotic pathogens in these farms may represent a risk for human health

The use of Bayesian methods for evaluating the performance of a virus-like particles-based ELISA for serology of hepatitis E virus infection in swine

International audienceIn the absence of commercial kits for serological studies specifically for hepatitis E virus (HEV) infection of swine, the capsid protein of a swine genotype 3 HEV was expressed using a recombinant baculovirus. This antigen was used in an enzyme-linked immunosorbent assay (ELISA) for detection of anti-HEV antibodies. Estimation of sensitivity and specificity was carried out in comparison with a commercial serological assay using sera from pigs infected experimentally with HEV genotype 3, negative sera from SPF pigs and swine sera collected at slaughterhouses. Since a "gold standard" is not available, a latent-class Bayesian approach for correlated tests was used to estimate the sensitivity and specificity of both tests. External field and experimental data were used to determine the parameters of Beta prior distributions. The estimated mean sensitivity of the commercial test was 0.47 with a 95% credibility interval of 0.39-0.55, whereas the estimated mean sensitivity of the genotype 3-based assay was 0.92 [0.81-0.99]. The estimated specificities were 0.98 [0.93-0.99] and 0.98 [0.95-0.99] for the genotype 3-based test and commercial test, respectively. in conclusion, genotype 3-antigen derived from swine HEV is a better candidate for assessing hepatitis E serology in swine

Estimating Parameters Related to the Lifespan of Passively Transferred and Vaccine-Induced Porcine Reproductive and Respiratory Syndrome Virus Type I Antibodies by Modeling Field Data

The outputs of epidemiological models are strongly related to the structure of the model and input parameters. The latter are defined by fitting theoretical concepts to actual data derived from field or experimental studies. However, some parameters may remain difficult to estimate and are subject to uncertainty or sensitivity analyses to determine their variation range and their global impact on model outcomes. As such, the evaluation of immunity duration is often a puzzling issue requiring long-term follow-up data that are, most of time, not available. The present analysis aims at characterizing the kinetics of antibodies against Porcine Reproductive and Respiratory Syndrome virus (PRRSv) from longitudinal data sets. The first data set consisted in the serological follow-up of 22 vaccinated gilts during 21 weeks post-vaccination (PV). The second one gathered the maternally derived antibodies (MDAs) kinetics in piglets from three different farms up to 14 weeks of age. The peak of the PV serological response against PRRSv was reached 6.9 weeks PV on average with an average duration of antibodies persistence of 26.5 weeks. In the monitored cohort of piglets, the duration of passive immunity was found relatively short, with an average duration of 4.8 weeks. The level of PRRSv-MDAs was found correlated with the dams’ antibody titer at birth, and the antibody persistence was strongly related to the initial MDAs titers in piglets. These results evidenced the importance of PRRSv vaccination schedule in sows, to optimize the delivery of antibodies to suckling piglets. These estimates of the duration of active and passive immunity could be further used as input parameters of epidemiological models to analyze their impact on the persistence of PRRSv within farms

Risk factors for Salmonella seroconversion of fattening pigs in farrow-to-finish herds

We did a prospective observational 9-month long study to quantify risk factors of managerial and hygiene practices, and pig-health status for Salmonella seroconversion of fattening pigs reared in subclinically infected French farrow-to-finish farms. During the fattening phase, 2 649 pigs belonging to the same batch of contemporary pigs, from 89 conventional farrow-to-finish farms were individually followed and regularly blood sampled on a monthly basis. Farm recruitment was based on the farmer's willingness to cooperate. Pig status was assessed using an indirect ELISA test. Evolution of the serological status was studied by means of survival analysis. A Cox proportional-hazards model, taking into account the clustering of animals at the farm level, was used to examine the effects of explanatory variables on the time to Salmonella seroconversion of pigs. Applying group level antibiotic treatment to the pigs during the fattening period (Hazard Ratio (HR) = 2.4; 95% CI: 1.7, 3.4) was identified as a risk factor for Salmonella seroconversion, as the presence of residual Salmonella contamination in the fattening pen before placing the pigs into the pens (HR = 1.9; 95% CI: 1.2, 2.9). Porcine reproductive and respiratory syndrome virus (PRRSV) seropositivity during the fattening period also indicated an increased hazard for seroconversion (HR = 1.6; 95% CI: 1.1, 2.5). The batch size was identified as a risk factor for Salmonella seroconversion: the higher the number of pigs was in the fattening room followed, the higher was the risk (HR$_{\rm +10 pigs}$ = 1.05 for a 10-pig increment; 95% CI: 1.03, 1.06). The biosecurity measures of wearing specific clothes before entering the facilities (HR = 0.5; 95% CI: 0.3, 0.9) and enclosing the pig farm facilities were protective (HR = 0.4; 95% CI: 0.2, 0.8)