The plague killed an estimated 10 million people and crippled the economy for a decade. It's believed however that the death toll could potentially have been many times worse, perhaps comparable to the 6th century Plague of Justinian, had it not been for major developments in hygiene and public health in the last hundred years. Indeed, in some parts of eastern Europe where hygiene theory was not so advanced, the plague killed up to 40% of the population in places, and is even today known there as the Black Death. By comparison, Rome, Persia, Egypt, Italy and most of the West survived relatively unscathed.