An innovative Surveillance analysis Tool for Outcome-based Comparison of FREEdom from infection in heterogeneous control programs
Résumé
Countries differ in existence, stage of eradication and design of control programs for non-regulated diseases. When freedom from infection is achieved, safe trade is essential to protect that status. The aim of STOC free, a collaboration between six countries, is to develop and validate a framework that enables transparent and standardized comparison of confidence of disease freedom for control programs across herds, regions or countries. The framework consists of a model (STOC free MODEL) combined with a tool to facilitate the collection of the necessary parameters (STOC free DATA). All actions taken in a control program will be included in a Bayesian model, which needs prior distributions for most parameters. Data for the distributions can be obtained from databases of control programs, demographic data and contact structures between herds. In addition, frequency of occurrence and risk estimates for factors that influence either the probability of introduction or delayed detection of the infection will be included in the model. Bovine viral diarrhea virus (BVDV) is used as an example disease. Many countries have control programs in place for this complex and detrimental disease with wide differences between application of vaccinations, combinations of diagnostic tests applied, frequency of testing and target groups. Although BVDV will be a thorough test of the initial developed framework, it should be generic enough to be adaptable to control programs for other diseases. With the introduction of the new Animal Health Law (AHL), it is anticipated that assessments of the performance of control programmes will progressively change towards output-based measures. The STOC free framework will support the AHL by providing a single general framework, adaptable to multiple diseases, which aims to enhance the safety of trade.