What Parts Work Together?

How do the parts of the bubonic plague system interact? Bubonic plague is caused by a bacteria called Yersinia pestis. This bacteria lives in fleas, which often ride on rats. Imagine it like a tiny hitchhiker. When the flea bites a rat, it transfers the bacteria to the rat, which sometimes makes the rat sick. People can get the plague if infected fleas bite them or if they come very close to sick animals. In simple terms, the bacteria, fleas, rats, and humans all play their parts in this disease story. The bacteria needs fleas to move, fleas need rats to live, and unfortunately, rats and humans can become hosts when bitten by those fleas.