title: Evaluation of farm-level parameters derived from animal movements for use in risk-based surveillance programmes of cattle in Switzerland.
abstract: BACKGROUND
  This study focused on the descriptive analysis of cattle movements and farm-level parameters derived from cattle movements, which are considered to be generically suitable for risk-based surveillance systems in Switzerland for diseases where animal movements constitute an important risk pathway.
  
  
  METHODS
  A framework was developed to select farms for surveillance based on a risk score summarizing 5 parameters. The proposed framework was validated using data from the bovine viral diarrhoea (BVD) surveillance programme in 2013.
  
  
  RESULTS
  A cumulative score was calculated per farm, including the following parameters; the maximum monthly ingoing contact chain (in 2012), the average number of animals per incoming movement, use of mixed alpine pastures and the number of weeks in 2012 a farm had movements registered. The final score for the farm depended on the distribution of the parameters. Different cut offs; 50, 90, 95 and 99%, were explored. The final scores ranged between 0 and 5. Validation of the scores against results from the BVD surveillance programme 2013 gave promising results for setting the cut off for each of the five selected farm level criteria at the 50th percentile. Restricting testing to farms with a score ≥ 2 would have resulted in the same number of detected BVD positive farms as testing all farms, i.e., the outcome of the 2013 surveillance programme could have been reached with a smaller survey.
  
  
  CONCLUSIONS
  The seasonality and time dependency of the activity of single farms in the networks requires a careful assessment of the actual time period included to determine farm level criteria. However, selecting farms in the sample for risk-based surveillance can be optimized with the proposed scoring system. The system was validated using data from the BVD eradication program. The proposed method is a promising framework for the selection of farms according to the risk of infection based on animal movements.
authors.affiliation: Veterinary Public Health Institute (VPHI), Vetsuisse Faculty, University of Bern, Bern, Switzerland. sara.schaerrer@vetsuisse.unibe.ch.
authors.forename: Sara
authors.initials: S
authors.lastname: Schärrer
authors.affiliation: National Veterinary Institute (SVA), Uppsala, Sweden. stefan.widgren@sva.se.
authors.forename: Stefan
authors.initials: S
authors.lastname: Widgren
authors.affiliation: Federal Food Safety and Veterinary Office (FSVO), Bern, Switzerland. heinzpeter.schwermer@blv.admin.ch.
authors.forename: Heinzpeter
authors.initials: H
authors.lastname: Schwermer
authors.affiliation: National Veterinary Institute (SVA), Uppsala, Sweden. ann.lindberg@sva.se.
authors.forename: Ann
authors.initials: A
authors.lastname: Lindberg
authors.affiliation: Veterinary Public Health Institute (VPHI), Vetsuisse Faculty, University of Bern, Bern, Switzerland. beatriz.vidondo@gmx.ch.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Vidondo
authors.affiliation: Swiss Tropical and Public Health Institute (Swiss TPH), University of Basel, Basel, Switzerland. jakob.zinsstag@unibas.ch.
authors.forename: Jakob
authors.initials: J
authors.lastname: Zinsstag
authors.affiliation: Federal Food Safety and Veterinary Office (FSVO), Bern, Switzerland. martin.reist@blv.admin.ch.
authors.forename: Martin
authors.initials: M
authors.lastname: Reist
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000517:prevention & control; D011159:Population Surveillance; D015203:Reproducibility of Results; D012307:Risk Factors; D012621:Seasons; D013557:Switzerland / Q000453:epidemiology; D014186:Transportation