Simulation studies of African horse sickness and Culicoides imicola (Diptera:Ceratopogonidae)

A simulation model of African horse sickness in Spain was developed to investigate what factors affect the likelihood of an epidemic after the introduction of the virus. The model included 2 host species (horses and donkeys) and 1 vector species (Culicoides imicola Kieffer). Latin hypercube sampling was used for sensitivity analysis of the model, to include uncertainty in parameter estimates. In general, if an epidemic occurred most hosts were infected. The peak prevalence in midges was low, and never exceeded 3%. Midge population size, the recovery rate in horses, and the time of year when the virus was introduced were the most significant factors in determining whether or not an epidemic occurred. The uncertainty in interbloodmeal interval, removal rate (mortality and recovery) of infectious horses, midge population size, and transmission rates were significant factors in the size of the epidemic. These factors should be priorities for empirical research, and should be considered in the design of control strategies in areas at risk of virus introduction.