title: Epidemiological investigation of bovine tuberculosis herd breakdowns in Spain 2009/2011.
abstract: We analyzed the most likely cause of 687 bovine tuberculosis (bTB) breakdowns detected in Spain between 2009 and 2011 (i.e., 22% of the total number of breakdowns detected during this period). Seven possible causes were considered: i) residual infection; ii) introduction of infected cattle from other herds; iii) sharing of pastures with infected herds; iv) contiguous spread from infected neighbor herds; v) presence of infected goats in the farm; vi) interaction with wildlife reservoirs and vii) contact with an infected human. For each possible cause a decision tree was developed and key questions were included in each of them. Answers to these key questions lead to different events within each decision tree. In order to assess the likelihood of occurrence of the different events a qualitative risk assessment approach was used. For this purpose, an expert opinion workshop was organized and ordinal values, ranging from 0 to 9 (i.e., null to very high likelihood of occurrence) were assigned. The analysis identified residual infection as the most frequent cause of bTB breakdowns (22.3%; 95%CI: 19.4-25.6), followed by interaction with wildlife reservoirs (13.1%; 95%CI: 10.8-15.8). The introduction of infected cattle, sharing of pastures and contiguous spread from infected neighbour herds were also identified as relevant causes. In 41.6% (95%CI: 38.0-45.4) of the breakdowns the origin of infection remained unknown. Veterinary officers conducting bTB breakdown investigations have to state their opinion about the possible cause of each breakdown. Comparison between the results of our analysis and the opinion from veterinary officers revealed a slight concordance. This slight agreement might reflect a lack of harmonized criteria to assess the most likely cause of bTB breakdowns as well as different perceptions about the importance of the possible causes. This is especially relevant in the case of the role of wildlife reservoirs.
authors.affiliation: National Animal Health Diagnostic and Investigation Center (NAHDIC), Sebeta, Ethiopia; Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Sintayehu
authors.initials: S
authors.lastname: Guta
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Departament de Sanitat i Anatomia Animals, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Casal
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Napp
authors.affiliation: Subdirección General de Sanidad e Higiene Animal y Trazabilidad, Dirección General de la Producción Agraria, Ministerio de Agricultura, Alimentación y Medio Ambiente, Madrid, Spain.
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Saez
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Ariadna
authors.initials: A
authors.lastname: Garcia-Saenz
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Bernat
authors.initials: B
authors.lastname: Perez de Val
authors.affiliation: Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Romero
authors.affiliation: Department of Veterinary Population Medicine, University of Minnesota, St Paul, Minnesota, United States of America.
authors.forename: Julio
authors.initials: J
authors.lastname: Alvarez
authors.affiliation: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Departament de Sanitat i Anatomia Animals, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Allepuz
mesh_terms: D000818:Animals; D002417:Cattle; D004196:Disease Outbreaks; D005843:Geography; D049673:History, 20th Century; D049674:History, 21st Century; D009163:Mycobacterium bovis; D062486:Public Health Surveillance; D013030:Spain / Q000453:epidemiology; D014380:Tuberculosis, Bovine / Q000453:epidemiology* / Q000266:history