A structured approach to control of Salmonella Dublin in 10 Danish dairy herds based on risk scoring and test-and-manage procedures

The aim of this study was to describe a structured approach to effectively reduce Salmonella Dublin prevalence in infected dairy herds based on a step-wise procedure. Furthermore, the aim was to describe tools for management and monitoring, and to report on development in prevalence among young stock and adult cattle in 10 case herds that were followed for more than three years. The five steps in the structured approach were: 1) risk scoring to determine transmission routes within the herd and into the herd: 2) determining a plan of action: 3) performing management changes to close important routes of infection; 4) interpretation of repeated testing of individual animals to detect high-risk animals for special hygienic management or culling; and 5) diagnostic testing of different age groups and bulk tank milk to evaluate progress of control over time. Serology, true prevalence estimates and changes in herd classification in the Danish surveillance programme for Salmonella Dublin were used to assess the progress in the herds during and after the control period. Effective control of Salmonella Dublin was achieved in all participating herds through management that focused on closing infection routes mainly in the calving areas and the young calf areas of the herds. It took on average three years to control the infection in the case herds. Bulk tank milk recordings from the four following years indicated that most of the herds might have eradicated the infection. (C) 2011 Elsevier Ltd. All rights reserved.