Final answer:
The plague, or Black Death, spread through infected rats bitten by fleas, which transmitted the bacteria to humans. Trade routes like the Silk Road facilitated its transmission across regions.
Step-by-step explanation:
The spread of the plague, also known as the Black Death, was primarily due to infected rats and fleas. Rats carried the bacteria Yersinia pestis, and when bitten by fleas, the bacteria would multiply in the fleas' gut. As the fleas moved from rat to rat, they spread the bacteria further.
This bacterial disease was then transmitted to humans when infected fleas bit them. The bacteria entered the human bloodstream, causing severe illness and often leading to death. Trade routes, such as the Silk Road, facilitated the transmission of the plague across vast regions.
During the 14th century, the plague spread rapidly throughout Europe and Asia, causing devastating loss of life and drastically reshaping societies and economies.
Learn more about spread of the plague