Effectiveness of movement-prevention regulations to reduce the spread of foot-and-mouth disease in The Netherlands.

After the foot-and-mouth disease (FMD) outbreak in 2001 the Dutch government implemented movement-prevention regulations to reduce the number of contacts between farms and consequently the risk of spread of highly contagious animal infections in the future. We studied the efficacy of these regulations by comparing registered cattle-movement data from 2000 to those from 2002. We also used the spatial and stochastic simulation model InterFMD to evaluate the consequences of the observed alterations in cattle-contact structure on the spread and control of a FMD epidemic. There was a significant decrease in the number of cattle movements "for live use", no difference in the number of group movements "for live use" and a distinct change in the overall contact structure. The most important structure changes were a decrease in the number of group movements from dairy farms to cattle-collection centres (-44%), and an increase in the number of group movements from dairy farms to beef farms (111%). Our simulations demonstrated that the implemented regulations result in a concentration of the FMD-affected area and therefore in a reduction in size of the epidemics. Based on the intended Dutch strategy to control future FMD outbreaks, the decrease in extreme epidemics (95th percentiles) went from 31 infected farms in an epidemic-length of 65 days to 8 infected farms in an epidemic-length of 53 days in sparsely populated areas. In densely populated areas this decrease went from 135 infected farms to 103, while the duration reduced from 88 days to 81.