title: Risk assessment as a tool for improving external biosecurity at farm level.
abstract: BACKGROUND
  Biosecurity routines at herd level may reduce the probability of introduction of disease into the herd, but some measures may be regarded as expensive and cumbersome for the farmers. Custom-made measures based on individual farm characteristics may aid in improving the actual application of on-farm biosecurity. The aim of the study was to provide a tool for calculating the effects of different biosecurity measures and strategies on the individual farm level. A simple model was developed to assess the risk of disease introduction and the need for biosecurity measures in individual farms. To illustrate the general applicability of the tool, it was applied to theoretical examples of Swedish cattle and pig farms and diseases endemic in those animal species in the EU, in two scenarios with different between-farm contact patterns.
  
  
  RESULTS
  The model illustrated that the most important factors affecting the risk, and the effect of biosecurity measures such as quarantine routines and protective clothing, were the frequency of between-farm contacts and prevalence of the disease. The risk of introduction as well as the effect of biosecurity measures differed between farm types and disease transmission routes. Adapting contact patterns to mitigate a specific disease risk was as important as biosecurity measures for some farm types, but the largest effect was seen when combining biosecurity measures with more planned contact patterns.
  
  
  CONCLUSIONS
  The risk assessment model proved useful for illustrating the risk of introduction of endemic diseases and the mitigating effect of different biosecurity measures on farm level. Model outputs could be used to justify prioritisation of measures or adapting contact patterns. The theoretic exercise of adjusting model inputs and comparing outputs may help veterinary advisors to understand farm-specific risks and motivate farmers to improve biosecurity in their individual farm, as it can be tailored to each farmer's needs and preferences.
authors.affiliation: Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7036, 75007, Uppsala, Sweden. susanna.sternberg-lewerin@slu.se.
authors.forename: Susanna
authors.initials: S
authors.lastname: Sternberg Lewerin
authors.affiliation: National Veterinary Institute, 75189, Uppsala, Sweden. julia.osterberg@sva.se.
authors.forename: Julia
authors.initials: J
authors.lastname: Österberg
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. stefan.alenius@slu.se.
authors.forename: Stefan
authors.initials: S
authors.lastname: Alenius
authors.affiliation: National Veterinary Institute, 75189, Uppsala, Sweden. marianne.elvander@sva.se.
authors.forename: Marianne
authors.initials: M
authors.lastname: Elvander
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. claes.fellstrom@slu.se.
authors.forename: Claes
authors.initials: C
authors.lastname: Fellström
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. madeleine.traven@slu.se.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Tråvén
authors.affiliation: National Veterinary Institute, 75189, Uppsala, Sweden. per.wallgren@sva.se.
authors.forename: Per
authors.initials: P
authors.lastname: Wallgren
authors.affiliation: National Veterinary Institute, 75189, Uppsala, Sweden. karin.persson-waller@sva.se.
authors.forename: Karin Persson
authors.initials: KP
authors.lastname: Waller
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Box 7054, 75007, Uppsala, Sweden. magdalena.jacobsson@slu.se.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Jacobson
mesh_terms: D000822:Animal Husbandry / Q000592:standards*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D008954:Models, Biological; D012307:Risk Factors; D013548:Sweden; D013552:Swine; D013553:Swine Diseases / Q000517:prevention & control*