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Utilisation des analyses en mélanges pour l'évaluation et le suivi du statut sanitaire des troupeaux : application à la paratuberculose des ovins

Abstract : Paratuberculosis is a contagious enzootic disease in ruminants caused byMycobacteriumavium ssp. paratuberculosis (Map). The long incubation period and the low informative values of antemortem diagnostic tests limit the effectiveness of control plans. In large sheep flocks, exhaustive individual testing is unfeasible and control plansmainly focus on vaccination, the effects of which have not yet been evaluated in French flocks. Using blood and feces samples from nearly 4000 ewes in 30 sheep flocks from the French department of Lot, the diagnostic performances of two serum ELISA and one fecal qPCR kits were estimated using bayesian and frequentist latent class modeling. Our results confirm the low sensitivity and non-perfect specificity of serum ELISA for the detection of subclinically infected animals, while the diagnostic performances of fecal qPCR were better. We also evaluated the relative diagnostic performances of pooled-sample analysis for both tests. Highly qPCR/ELISA positive samples were invariously detected while low positive ones were associated with lower detection rates. The flock-level epidemiological performances of screening strategies based on pooled-sample analysis were evaluated by simulation studies. Pooled serum ELISA appeared lowly specific. Conversely, pooled fecal qPCR appeared promising, allowing the detection of low infection prevalence. Finally, the work carried out in the vaccinated flocks made it possible to better know their epidemiological status and to specify to what extent it could be approached using pooled-sample analysis.
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Submitted on : Wednesday, April 3, 2019 - 3:51:46 PM
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Yoann Mathevon. Utilisation des analyses en mélanges pour l'évaluation et le suivi du statut sanitaire des troupeaux : application à la paratuberculose des ovins. Médecine vétérinaire et santé animale. Université Paul Sabatier - Toulouse III, 2018. Français. ⟨NNT : 2018TOU30044⟩. ⟨tel-02089274⟩

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