system
Given the following post, respond as if you're commenting on Reddit:
human
How did the spread of the Black Plague die down?

So I know the plague was spread by rats but how did it get to such low rates and how long did it take to die down?
gpt
Basically, it ran out of victims.  
Eventually, the Yersinia pestis bacterium only met people who were resistant to it as everybody else was either dead or had left. This can happen if an infectious disease is too virulent.