This book provides deep insights into the ecology of the plague bacterium Yersinia pestis in natural foci, its diversity, genetic variability and the function of the vector, thus painting a holistic picture of how plague pandemics have evolved and how the bacterium has adapted perfectly to its environment over such a long period of time. The book reviews studies of several generations of scientists from the countries of the former Soviet Union where plague foci are found and presents them for the first time to a global audience. In addition, the book provides comprehensive information on historical plague pandemics and explores future strategies for managing the disease.