**Preface to "Classical Swine Fever"**

With several currently prevalent swine diseases, classical swine fever (CSF), one of the most ancient swine diseases, has been almost forgotten. However, by no means is our fight against CSF over. On the contrary, its ghost still lingers, waiting for an opportunity to show itself. For example, in the year 2018 the reemergence of CSF in previously CSF-free areas caused significant economic losses in a short period. Moreover, it still sporadically or endemically appears in many corners of the world, causing lingering little-noticed but significant economic loss. Over the past 20 years, the advances in the CSF field have been more focused on the molecular, biological, or intracellular aspects of the CSF virus, with few advances in diagnostics and vaccines. Those veterinary colleagues that have not abandoned the old ship find it difficult to compete for grants and find academic conferences lonely. In the year 2018, the reemergence of CSF facilitated an opportunity, offered by the journal Pathogens (MDPI), to gather together colleagues to speak on CSF at the animal, population, and molecular levels, relating to the disease aspects of CSF. Certainly, the articles collected in this book do not cover the whole CSF situation worldwide. For example, we do not hear from Eastern Europe, Southern America, or Africa. In particular, we are curious to hear how those CSF-free areas maintain their CSF-free status. Despite these limitations, we hope that this book will provide useful references for our colleagues, whether you are in a CSF-free or CSF-affected part of the world, and whether you are a policy maker, practicing veterinarian, or laboratory scientist.

> **Fun-In Wang, Chia-Yi Chang** *Editors*
