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

Abstract

The application of a computer model called Rimpuff for simulating the airborne spread of foot-and-mouth disease (FMD) is described. Rimpuff is more sophisticated and accurate than other FMD simulation models previously described. It can be run on a desktop computer and performs analyses very quickly. It can be linked to a geographical information system and so the information generated can be integrated with geographical and demographical data for display in a format that can be easily assimilated and transmitted electronically. 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 Democratic 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 disease from France to the UK in 1981. Although cattle in the UK were infected during the episode, the concentrations of airborne virus in the plumes simulated 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 much higher than was recorded at the time of the outbreaks. Analysis of the Denmark/GDR episode pointed to the possibility that the source of virus for the 1982 epidemic in Denmark could have been one or more unreported outbreaks involving pigs in the former GDR.

Investigation of airborne foot-and-mouth disease virus transmission during low-wind conditions in the early phase of the UK 2001 epidemic

“…Both the local-scale RIMPUFF and the long range DERMA model have previously been used for the retrospective estimation of the dispersion of the FMD virus (Sørensen et al, 2000. Calculations performed showed that the long-range DERMA calculations gave similar results to the long range NAME model.…”

“…The risks of airborne spread were first analysed using data for historical strains of virus, which are excreted in high quantities by infected pigs Sørensen et al, 2000). These therefore gave "worst-case" scenarios for predicted spread.…”

“…Firstly the amounts of virus emitted from the outbreak at Burnside Farm were calculated using the original Virus Production Model (VPM) (Sørensen et al, 2000). But as new experimental virus excretion data became available for the UK 2001 strain of virus , the predictions were all re-calculated.…”

“…In previous outbreaks it has been concluded that the quantities of viral emissions from pigs were sufficiently large for infectious concentrations to be present at a distance up to 100 km or more from the source, even in moderate winds (Sørensen et al, 2000).…”

A decision-tree to optimise control measures during the early stage of a foot-and-mouth disease epidemic

“…Under certain epidemiological and climatic conditions FMD virus can be spread by the wind. Of all mechanisms spread by air is least controllable Ferguson et al, 2001a;Sorensen et al, 2000Sorensen et al, & 2001.…”