>>212810358
They originally though dogs and cats were causing the plague but it was really the fleas on them. They held the bacteria inside them and since dogs/cats are immune to the bacteria, it didn't affect them.
SO they killed all the cats and dogs, which meant the fleas jumped onto humans instead and spread the disease even faster.
At one point they thought it was jews poisoning them so they rounded up and burned shitloads of jews. In one case they suspected the well had been poisoned so they threw a rabbi down the well and left him there to die.
The closest anyone got to understanding it was Miasma Theory which refers to "bad air". They thought swamp air caused it, but really it was just biting insects that live in swamps who carried the bacteria and infected people.
