Sensitivity analysis of a stochastic simulation model for foot and mouth disease

I Traulsen,J Krieter,G Rave

doi:10.5194/aab-53-529-2010

Abstract

Abstract. A spatial and temporal Monte-Carlo simulation model was developed to analyse the epidemiology and control of foot and mouth disease (FMD). Animal, people and vehicle contacts as well as airborne and local spread represented the FMD virus transmission between farms housing cattle, pigs or sheep. Contacts were explicitly modelled by routes, airborne transmission by the Gaussian Dispersion model and local spread by distance dependent transmission probabilities. Control measures were implemented according to the EU Directive (2003/85/EG). A sensitivity analysis with a two-level fractional factorial design was used to examine the robustness of the simulation model to extreme input values. The influence of eleven input parameters and interactions between them were estimated: ability of airborne spread, duration of the incubation period, time from infection until infectivity, time from onset of clinical signs until diagnosis, farm density, type of index case, number of farms visited per route, visiting interval, type of the animal sales, control strategy, and delay until start of control strategies. The considered parameters as well as certain two-factor interactions between them showed a significant impact on the epidemic duration and the number of infected and culled farms. Particularly, the parameter airborne spread, farm density, number of farms visited per route and control strategy influenced the course of the epidemic. The consideration of airborne spread as well as the implementation of contacts between farms with routes allowed a detailed analysis of these transmission paths.

Highlights

Foot and mouth disease (FMD) is a highly contagious OIE (Office International des Epizooties) listed disease that can spread rapidly and widely among all cloven-hoofed animals (DONALDSON et al 2001, NISSEN et al 2003, KITCHING et al 2005)
Simulation models are a feasible mean to gain better insight into the processes of the epidemiology of FMD virus and to evaluate control strategies against FMD, for countries that are free from the disease (GREEN and MEDLEY 2002, GARNER et al 2007, KARSTEN et al 2007)
Epidemiological models for FMD have been developed for different countries (FERGUSON et al 2001, BATES et al 2003a, PEREZ et al 2004, MENACH et al 2005, CARPENTER et al 2007, GARNER et al 2007, HARVEY et al 2007, KOBAYASHI et al 2007a, WARD et al 2009)

Summary

Introduction

Foot and mouth disease (FMD) is a highly contagious OIE (Office International des Epizooties) listed disease that can spread rapidly and widely among all cloven-hoofed animals (DONALDSON et al 2001, NISSEN et al 2003, KITCHING et al 2005). Simulation models are a feasible mean to gain better insight into the processes of the epidemiology of FMD virus and to evaluate control strategies against FMD, for countries that are free from the disease (GREEN and MEDLEY 2002, GARNER et al 2007, KARSTEN et al 2007). Epidemiological models for FMD have been developed for different countries (FERGUSON et al 2001, BATES et al 2003a, PEREZ et al 2004, MENACH et al 2005, CARPENTER et al 2007, GARNER et al 2007, HARVEY et al 2007, KOBAYASHI et al 2007a, WARD et al 2009). A stochastic simulation model with special focus on the simultaneous estimation of the airborne spread and the modelling of contacts between farms is presented. A sensitivity analysis was performed to test the models’ robustness to extreme values of the input parameter and to identify risk factors that are to be included in further applications of the model

Methods

Results

Conclusion