Answer:
B. Bubonic plagues
Explanation:
Bubonic plague is caused by Yersinia pestis. Rats, prairie dogs and squirrels are the pests that harbour the disease while fleas serve as vector, carrying the Yersinia pestis to humans.
The human victim either touches a dead infected rodent or is bitten by an infected flea. The bacteria invade the skin and are gobbled up by macrophages. They continue to reproduce intercellularly and within lymph nodes especially the inguinal nodes. The nodes swell like eggs and become hot, red and painful. Fever and headache sets in. Hemorrhages under the skin cause a blackish discoloration leading people to call bubonic plague the "Black Death."
Without treatment, death occurs within a few days. Treatment is with antibiotics such as streptomycin, doxycycline.
