Summary
Objectives:
The application of epidemic models during the first days following the confirmation of a virus outbreak should significantly contribute to minimize its costs. Here we describe the first version of a decision-support system for the calculation of the airborne spread of a virus and its application to foot-and-mouth disease (FMD). The goal is to provide geographical maps depicting infection risk for various animal species to support the national health authorities.
Methods:
The major tool of the decision-support system is a specific epidemic (or atmospheric) model: A so-called Gaussian dispersion model to calculate 3-dimensional virus plumes. Additional tools providing input data and visualizing the output are: A veterinary data base of geo-referenced premises, a geographical information system (GIS), and, as an external part running at the National Weather Service, a numerical weather prediction (NWP) model. To demonstrate the features of the decision-support system a pilot study in Styria, Austria, has been performed simulating an artificial FMD outbreak.
Results:
One result of this simulation experiment is the determination of neighboring premises at which animals are at risk to be infected. Particular attention has been turned to cattle, sheep and swine. Using actual hourly NWP data from April 25, 2003, and a source of ten swine excreting a virus, cattle have been estimated to be at risk downwind 1,000-12,000 m, sheep 200-1,300 m, and swines 70-330 m.
Conclusions:
A system for real-time risk assessment of the airborne spread of a virus, applied to FMD, was introduced. Due to the forcing of the Gaussian dispersion model with NWP data, it is designed to run in both analysis and forecast mode. The system was applied for the first time during the Austrian real-time exercise on FMD, instructed by the European Union, in November 2004.
