Mart de Jong is chairholder of the QVE Chairgroup. This chairgroup focuses on modelling and quantifying the interactions (transmission) between animals with respect to infections. We do this to determine the factors that have large effect on this transmission and to quantify the effect of interventions. We study the mechanisms underlying the transmission by using mathematical models, observational techniques and experiments. By better understanding the underlying mechanisms we can better measure and extrapolate the effect of interventions. For example for hygiene and biosecurity interventions we need to understand the behaviour of the infectious agent in the environment. Another intervention we have worked on a lot is the effect of vaccination on transmission.