The ship treater is on his way to find someone to tread when he sees a rat. He does not care because he sees rats all the time. But he does not know that fleas got on the rat has the plage.(black death.)
When he gets to the dock he gives the box to the treater but he does not know that he has the black death and that is how it spreads.
When the seller gets back he puts the box in his room. The next morning he has black dots all over his arms and face. He dies by coughing in the mom's face. The she spreads it all over the place.
All of the farmers got sick by the black death. But they did not know it was the black death. They thought it was the gods were punishing them.
The nobles and kings were safe because they were safe inside. But all the people outside were dying by the black death
Now today we have medon to keep us safe from the black death. Not a lot of people dye to the black death.