Yersinia pestis, the organism that causes the bubonic plague, led to the deaths of approximately 75 million people is the 1300's. This was known as the Black Death. Which type of organism caused the bubonic plague?

Yersinia pests

Explanation:

it is  a bacterium. its vectors is infected flea from an animal.  The plague  can also results from contact with contaminated fluid from dead infected animal   from bubonic plague.

when the flea bites, the bacterium enters the blood stream and through the lymphatic systems it finds it way into the lymph nodes of the armpit and pubic region.

it localized in the nodes leading to swelling, enlarged nodes-buboe, with  painful sensation.

chills, high fever, seizures, are some of the symptoms.

proper hygiene is the best preventive methods.

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