Potential ecological and epidemiological factors affecting the persistence of classical swine fever in wild boar Sus scrofa populations

1. Classical swine fever has increased in economic importance since it has become endemic in some wild boar Sus scrofa populations in Europe. The mechanism of disease persistence is still not well understood, and several aspects of both the ecology of boar and the virus are claimed to be responsible for disease persistence. 2. We review literature on the spread and persistence of the disease in free-ranging wild boar. We determine whether the available knowledge can explain the observed patterns via mechanistic processes and their interactions, and assemble knowledge in a conceptual model. 3. We speculate that the most important factor explaining disease persistence is an alteration in disease outcome, resulting in individual courses with prolonged infectiousness or a sustained reproductive population through immunity. This effect is reinforced by high wild boar numbers either within sites or scattered over larger areas. 4. We highlight the sparse knowledge of disease transmission between wild boar. We derive management suggestions for different phases of an outbreak based on the conceptual model and advocate the use of model-based investigations to test alternative management options.