How did the black death stop in the end?

Answer 1

Disease spreads more easily in crowded cities with lots of people living close to each other; during the Black Death in Europe, so many people died that the cities became much less crowded, and even those who survived in many cases fled from the cities, so it became harder for the disease to spread. In addition, there is an evolutionary effect, because at some point those who are most susceptible die, and those who did not die have some resistance. Furthermore, although the black death is no longer killing large numbers of people, it is not really gone, either. Some people still die of Bubonic Plague.