In "Absolute War", Chris Bellamy opens with an interesting anecdote about the spread of rabies through Western Europe, which could be tracked as it progressed towards the Channel in the 1960s. The reason for the westward movement of the disease is ascribed to World War II, and the advance of the Red Army from '43-'45, which massively displaced the wolf and fox populations of Eastern and Central Europe, forcing them further west in great concentrations, the effects of which were then felt for decades after. He mostly cites this article from 1969, but I don't have access to it, so can't expand on more than he mentioned.