Question

how did the bubonic plague spread across continents during the middle ages? through direct person - to - person contact by contaminated trade items through rats and fleas

Explanation:

The bubonic plague, also known as the Black Death, was primarily spread by infected fleas that lived on rats. These rats were common on ships and in trade routes during the Middle Ages. When the fleas bit humans, they transmitted the Yersinia pestis bacteria that caused the plague. While person - to - person contact (through respiratory droplets in the case of pneumonic plague, a related form) and contaminated items could play some role, the main vector was rats and fleas.

Answer:

through rats and fleas