There is no gentle way to introduce the Black Death; it was the deadliest of human pandemics. Sweeping across mainland Europe in 1347, it killed about one-third of the population in the following 5 years. So many people died, that it took 300 years for the population of Europe to return to pre-pandemic levels. The death rate varied substantially between countries. While Scandinavia, France, Germany, Greece and central Italy experienced high mortality, Spain, Ireland and countries in Eastern Europe were relatively spared [1–3].