First serological evidence of Q fever circulation in ruminant herds in French Guiana

International audienc

FOXP3, CD208, and CD206 Expression in Canine Cutaneous Histiocytoma

Canine cutaneous histiocytoma (CCH) is a noninfectious tumor that spontaneously regresses. It is suggested that this regression is due to tumor cell maturation, which is responsible for CD8 lymphocyte activation and tumor cell destruction. Nevertheless, the possible role of the immune microenvironment in tumor regression has not been investigated to date. The aim of this study was to investigate the expression of CD208 and FoxP3 as markers of dendritic cells and regulatory T lymphocytes, respectively, and tumor cell expression of CD206 as a marker of Langerhans cell activation, and relate these parameters to the different phases of CCH and to intratumoral T cell infiltration. Formalin-fixed, paraffin-embedded samples from 31 CCH were evaluated. In each case, the mitotic count and regression phase were recorded. Within the tumor, a quantitative evaluation of immunolabeled CD208+ cells, FoxP3+ cells, and CD3+ lymphocytes was performed, as well as the CD206+ tumor cell location. Intratumoral CD208+ cells correlated with CD3+ lymphocytic infiltration. The possible role of dendritic cells in tumor regression was not confirmed since CD208 seemed to be a nonspecific marker for canine dendritic cells. FoxP3+ lymphocyte density was not correlated with any parameter. Neoplastic Langerhans cells presented progressive CD206 expression, from the bottom of the tumor to the epidermis, which correlated with the tumor regression phase and with intratumoral T lymphocyte infiltration. In conclusion, we confirmed a CD206 phenotype change in tumor cells in a spatial group-related pattern, supporting the hypothesis that tumoral Langerhans cells acquire a mature phenotype with tumor regression

Performances des méthodes diagnostiques de la fièvre Q chez les ruminants domestiques : état de l’art et intérêt de l’activité de référence du LNR

International audienceLa fièvre Q est une maladie zoonotique causée par la bactérie Coxiella burnetii, la plupart des cas cliniques humains recensés sont liés à une exposition à des ruminants domestiques excréteurs de la bactérie. Parmi les méthodes diagnostiques des infections par C. burnetii en élevages de ruminants, les méthodes PCR et ELISA sont recommandées respectivement pour le diagnostic direct et indirect par l’EFSA et l’OIE. Cet article fait l’état des lieux des connaissances sur les performances analytiques et diagnostiques de ces méthodes. Il présente également les moyens mis en œuvre par le LNR fièvre Q pour contribuer à standardiser ces méthodes et à valider leurs performances (PCR) ou les évaluer (ELISA), et ainsi garantir comparabilité et fiabilité des résultats fournis par un réseau de laboratoires. Les travaux mis en œuvre par les équipes de recherche (bactériologie, épidémiologie, statistiques) et le LNR ont permis de préciser l’interprétation des résultats diagnostiques de la fièvre Q chez les ruminants domestiques. Les recommandations d’usage de ces tests, dans le contexte de l’imputation d’une série abortive à C. burnetii dans les élevages de ruminants (protocole national du dispositif OSCAR), sont discutées à la lumière des nouvelles connaissances. Poursuivre ces travaux permettra d’appuyer davantage la démarche diagnostique des vétérinaires praticiens, la surveillance nationale et internationale et les échanges

Efficacy of a targeted selective treatment in dairy herds affected by clinical dictyocaulosis.

International audienceBovine dictyocaulosis is a pulmonary disease caused by the presence and development of the strongyle Dictyocaulus viviparus in the trachea and bronchi of cattle. This parasite is mostly observed in temperate countries, with potential important clinical and economical impacts. Individuals that already had contact with the parasite normally develop a strong acquired immunity. However, when the first contact with the parasite was poor and the contamination of the environment is high, clinical signs can occur. In such a context of clinical dictyocaulosis outbreak in dairy herds, current recommendations are to treat the whole herd with anthelmintic because of the presence of subclinical infestations. However, current guidelines against anthelminthic resistance recommend the use of selective treatment on adult cattle in order to maintain a refuge helminth population unexposed to anthelmintic. According to the heterogeneity of acquired immunity in a herd, and hence, of sensitivity of animals to parasitic infestation by D. viviparus, an early targeted selective treatment of clinically affected and main shedders animals may be effective to control the disease in the herd. Such a strategy was never tested for dictyocaulosis and a field validation is thus necessary to ensure a proper control of ditycocaulosis at the herd level.ObjectivesThis study is a pilot study designed to assess the clinical relevance of a targeted selected treatment against D. viviparus at the beginning of a dictyocaulosis outbreak in dairy herds.Materials and methods. In each herd with clinical signs of dictyocaulosis, we performed broncho-alveolar lavage on 6 cows and a pooled McKenna sedimentation on 10 cows of the herd to test for the presence of D. viviparous. We implemented a targeted selective treatment in three positive dairy herds by treating with injectable eprinomectine approximately 50% of the dairy cows including clinically affected, primiparous and postpartum cows. The follow-up was implemented one and three months after the targeted selected treatment by performing broncho-alveolar lavage and a pooled McKenna sedimentation. The farmers recorded clinical signs of dictyocaulosis at the herd level during the whole study period.ResultsIn the three followed dairy herds, symptoms of dictyocaulosis vanished after the targeted selective treatment. After the treatment, we assessed a dictyocaulosis incidence rate of 2% by month during the whole follow-up, which indicates a low but persistent circulation of the parasite in the herd. Clinical signs of dictyocaulosis, remained very low to inexistent in the three herds during the whole study period. ConclusionThe targeted selective treatment implemented in the three herds of this study was efficient to control dictyocaulosis at the herd levels. To our knowledge, this study is the first to prove the potential interest of a targeted selective treatment to control dictyocaulosis at the herd level. These results should be confirmed in a larger study with more herds

Interpretation of the results of Q fever ELISA tests in domestic ruminants : a user-friendly Shiny appli-cation based on latent class models in a Bayesian framework

International audienc

Interpretation of the results of Q fever ELISA tests in domestic ruminants : a user-friendly Shiny appli-cation based on latent class models in a Bayesian framework

International audienc

Interpretation of the results of ELISA tests commercialized for the serological diagnosis of Coxiella burnetii infection in domestic ruminants: a user-friendly Shiny application based on latent class models in a Bayesian framework

International audienceQ fever is a worldwide zoonotic disease, due to the bacterium Coxiella burnetii, responsible for reproductive disorders, such as abortion in domestic ruminants. Although direct detection of C. burnetii by quantitative PCR is primarily recommended for the direct diagnosis of Q fever in abortive contexts and identification of bacterial shedding, serological approaches aiming at detecting antibodies specific for C. burnetii are also useful at both the individual and herd levels. At the individual level, ELISA tests may be used to identify animals that were previously infected (with or without clinical signs and shedding) and may still be latently infected (carriers with or without shedding). At the herd level, ELISA tests may be used to reveal a past or recent exposure to C. burnetii within a considered farm, a key tool for a rapid screening (prevalence, current evolutive circulation). Recent investigations about the diagnostic accuracy of the three ELISA tests currently commercialized for their use in domestic ruminants showed that these tests are moderately sensitive (sensitivity values ranged between 40% and 94%) and that their specificities are inferior to 100% (specificity values ranged between 95% and 99%). As a consequence, the diagnostic uncertainty should be considered to limit potential misinterpretations of the individual or herd serological status.ObjectivesThe objectives of this study were (1) to build a methodological framework allowing calculating predictive values of Q fever ELISA tests at both the individual and the herd levels and (2) to provide a user-friendly application that could be easily used by veterinarians to interpret the results of a serological sample plan applied to a ruminant herd. Materials and methodsWe developed an advanced computing method based on latent class modeling, implemented using JAGS and R to calculate predictive values corresponding to the results obtained with any of the three commercialized ELISA tests, at both the individual and the herd levels. This method was integrated within an open source web application, using Shiny, to favor its accessibility to all the potential users of these ELISA tests (e.g., veterinarians, veterinary diagnostic laboratories, research laboratories). After completing the characteristics of the herd (species, herdsize, type of production) and the Q fever epidemiological context (if known), the users obtain the probability of true seropositivity of the tested herd and animals given the ELISA test results. The operation of this application is illustrated on a true clinical case where a Charolais bull originating from an apparently ‘free of infection’ herd was tested positive for Q fever by one ELISA test at introduction. To confirm or infirm these test results, additional animals in the herd of origin were tested with the same ELISA, considering firstly five heifers raised with the bull and secondly all males and females more than two-year-old (N=149). Probabilities of true seropositivity of the bull and its originating herd were calculated thanks to the developed application.ResultsThe five other animals initially tested animals that were raised with the seropositive bull were negative to the ELISA test, which corresponds, in regard to the test used and to the herd characteristics to a probability of the bull’s true seropositivity estimated at 0.85 with a 95% credibility interval (CI) of [0.14; 0.98].Among the animals older than two years present in the herd, 5 out of the 149 tested animals tested positive which corresponds for each positive animal to a probability of true seropositivity estimated at 0 with a 95% CI of [0 ; 0.65]. At the herd level, the probability that the proportion of seropositive animals was above 0 was estimated at 0 with a 95% CI of [0 ; 0.58]; and if the herd was truly seropositive, the proportion of truly seropositive animals in the herd was assessed to 0.06 with a 95% CI of [0.02; 0.12].ConclusionThis application assists veterinarians in a proper interpretation of the results of Q fever ELISA tests according to the sampling size and to available epidemiological and herd information. Veterinarians can therefore easily take advantage of a complex statistical model in a Bayesian framework to support their daily work related to Q fever risk analysis in ruminants. In the absence of a perfect reference test, this application could also be useful for local and reference laboratories for the confirmatory diagnosis of an ELISA test result

Méthode utilisée pour redéfinir les seuils de positivité du test Interféron Gamma utilisé dans le cadre du programme de surveillance de la tuberculose bovine

National audienc

Diagnosis of bovine dictyocaulosis by bronchoalveolar lavage technique: A comparative study using a Bayesian approach

International audienc

Diagnosis of bovine dictyocaulosis by bronchoalveolar lavage technique: A comparative study using a Bayesian approach

International audienc