Middle Ages

The Black Plague killed 1/5 of the population of Europe.  How could this have happened?
Where did the Black Death come from and how was it spread???

What role did I play?

Do we have any diseases today that are spread in a similar manner?
What about malaria?  How was it spread?

Can you name another current disease?  How is this disease spread?

How did the feudal system change as a result of the Black Death?