Simulating control of a focal wildlife outbreak of Echinococcus multilocularis.

The parasitic tapeworm Echinococcus multilocularis is the causative agent of alveolar echinococcosis, a serious zoonotic infection present in Europe that can be fatal. The United Kingdom currently has E. multilocularis free status but the possibility of introduction exists, most likely via an imported or returning dog or other deliberately introduced animal that has not had anthelmintic treatment. We have developed a model to predict the probability of successfully eliminating a focal outbreak of E. multilocularis using a programme of anthelmintic bait distribution. We investigated three different potential control programmes, each with 36 monthly campaigns commencing five, ten or 15 years after disease introduction over an area of 2827km. We assumed equilibrium disease prevalence of 30%, 40% and 55% based on the range of values reported across Europe. However, for all of these scenarios, equilibrium had not been reached at five to 15 years after introduction and simulated local prevalence values were between 0.5% and 28%. We found that it is possible to eliminate the disease with a 38%-86% success rate if control is started five years after introduction, dropping to 0% to 56% if control is delayed until 15 years after introduction, depending upon the prevalence equilibrium. We have also estimated the costs involved in these programmes to be from €7 to €12 million (2013 prices).