Minimization of the Impact of Aujeszky’s Disease Outbreaks in The Netherlands: A Conceptual Framework

In the Netherlands, outbreaks of Aujeszky’s Disease (AD) are controlled by vaccination and movement restriction zones (MRZ). Although this strategy avoids the socio-ethical concerns associated with pre-emptive slaughter, it can easily result in animal welfare problems and negative economic consequences. These arise because movement restrictions result in surpluses of live (vaccinated) piglets on farms. The aim is to provide insight into the development of these surpluses and its impact and to describe how measures that allow early transportation of pigs under certain conditions and to specific destinations (channelling) could reduce these problems. For the analysis, a deterministic simulation model was developed, which calculates surpluses of piglets at multiplier farms during AD outbreaks. This is performed on a weekly basis for two areas (with and without piglet surplus), three outbreak durations (minimum, moderate and long) and three strategies for movement restrictions (strict, transports within the MRZ allowed and transports outside the MRZ allowed). The results show that in case of complete movement restrictions, surpluses of piglets varying in age and vaccination status will quickly arise. These surpluses are larger for longer epidemics and can become as large as 180–340 thousand piglets (45–75% of weekly domestic production) for moderate and long epidemics, respectively. Implementation of channelling strategies that allow earlier transportation within the MRZ can reduce surpluses by about 50% to 100–150 thousand piglets maximum. Strategies that also allow transportation outside the MRZ can reduce surpluses even further to below 100 thousand piglets. It was concluded that channelling of live piglets during AD outbreaks results in a drastic reduction of problems with accommodating ready-for-transport piglets. Moreover, it reduces shortages during movement restrictions and peak supply immediately after removing the restrictions. Channelling could therefore be an important instrument to reduce the economic and animal welfare impacts of containment measures.