title: Modelling of paratuberculosis spread between dairy cattle farms at a regional scale.
abstract: Mycobacterium avium subsp. paratuberculosis (Map) causes Johne's disease, with large economic consequences for dairy cattle producers worldwide. Map spread between farms is mainly due to animal movements. Locally, herd size and management are expected to influence infection dynamics. To provide a better understanding of Map spread between dairy cattle farms at a regional scale, we describe the first spatio-temporal model accounting simultaneously for population and infection dynamics and indirect local transmission within dairy farms, and between-farm transmission through animal trade. This model is applied to Brittany, a French region characterized by a high density of dairy cattle, based on data on animal trade, herd size and farm management (birth, death, renewal, and culling) from 2005 to 2013 for 12,857 dairy farms. In all simulated scenarios, Map infection highly persisted at the metapopulation scale. The characteristics of initially infected farms strongly impacted the regional Map spread. Network-related features of incident farms influenced their ability to contaminate disease-free farms. At the herd level, we highlighted a balanced effect of the number of animals purchased: when large, it led to a high probability of farm infection but to a low persistence. This effect was reduced when prevalence in initially infected farms increased. Implications of our findings in the current enzootic situation are that the risk of infection quickly becomes high for farms buying more than three animals per year. Even in regions with a low proportion of infected farms, Map spread will not fade out spontaneously without the use of effective control strategies.
authors.affiliation: INRA, UR1404 Unité Mathématiques et Informatique Appliquées du Génome à l'Environnement (MaIAGE), F-78352, Jouy-en-Josas Cedex, France. gael.beaunee@gmail.com.|INRA, LUNAM Université, Oniris, UMR1300 BioEpAR, CS40706, F-44307, Nantes, France. gael.beaunee@gmail.com.
authors.forename: Gaël
authors.initials: G
authors.lastname: Beaunée
authors.affiliation: INRA, UR1404 Unité Mathématiques et Informatique Appliquées du Génome à l'Environnement (MaIAGE), F-78352, Jouy-en-Josas Cedex, France. elisabeta.vergu@jouy.inra.fr.
authors.forename: Elisabeta
authors.initials: E
authors.lastname: Vergu
authors.affiliation: INRA, LUNAM Université, Oniris, UMR1300 BioEpAR, CS40706, F-44307, Nantes, France. pauline.ezanno@oniris-nantes.fr.
authors.forename: Pauline
authors.initials: P
authors.lastname: Ezanno
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000635:transmission* / Q000821:virology; D003198:Computer Simulation; D003612:Dairying / Q000379:methods*; D003710:Demography; D005602:France / Q000453:epidemiology; D008954:Models, Biological; D016927:Mycobacterium avium subsp. paratuberculosis / Q000502:physiology*; D010283:Paratuberculosis / Q000635:transmission* / Q000821:virology; D015995:Prevalence