An integrated model to predict the atmospheric spread of foot-and-mouth disease virus

The application of a computer model called Rimpuff for simulating the airbo rne spread of foot-and-mouth disease (FMD) is described. Rimpuff is more so phisticated and accurate than other FMD simulation models previously descri bed, It can be run on a desktop computer and performs analyses very quickly . It call be linked to a geographical information system and so the informa tion generated can be integrated with geographical and demographical data f or display in a format that can be easily assimilated and transmitted elect ronically. The system was validated using historical data from outbreaks of FMD in France and the UK in 1981, and from Denmark and the former German D emocratic Republic (GDR) in 1982. A very good fit was obtained between the direction of the plumes of virus simulated by the model and the spread of d isease from France to the UK in 1981. Although cattle in the UK were infect ed during the episode, the concentrations of airborne virus in the plumes s imulated by the model were beneath the infectivity threshold for cattle. It was concluded from the analysis that the number of pigs infected in France , and therefore the source concentration of airborne virus, was probably mu ch higher than was recorded at the time of the outbreaks. Analysis of the D enmark/GDR episode pointed to the possibility that the source of virus for the 1982 epidemic in Denmark could have been one or more unreported outbrea ks involving pigs in the former GDR.