Answer:
Hello.
It was from fleas on rats, the plague first spread to humans near the Black Sea and then out towards the rest of Europe as a result of people fleeing from one area to another. Rats migrated with humans, traveling among grain bags, clothing, ships, wagons, and grain husks.
Explanation:
The Black Death was an epidemic which ravaged Europe between 1347 and 1400. It was a disease spread through contact with animals (zoonosis), basically through fleas and other rat parasites (at that time, rats often coexisted with humans, thus allowing the disease to spread so quickly).
Even then, a rat was the main one spreading the plague around to humans.