Bubonic plague

Bubonic plague is one of three types of plague caused by the bacterium Yersinia pestis. One to seven days after exposure to the bacteria, flu-like symptoms develop. These symptoms include fever, headaches, and vomiting, as well as swollen and painful lymph nodes occurring in the area closest to where the bacteria entered the skin. Acral necrosis, the dark discoloration of skin, is another symptom. The plague is considered the likely cause of the Black Death that swept through Asia, Europe, and Africa in the 14th century and killed an estimated 50 million people, including about 25% to 60% of the European population.

Quotes

 * In the XXII. yere were grete reynes, whech dured fro the Nativite of Seynt Jon Baptist onto Cristmasse.And aftir that reyne there folowid a grete pestilens, specialy in the Est side of the world amongst the Sarasines. So many deied, that there left scarsly among hem the tenth man, or the tenth woman. Thei, seyng this veniauns amongst hem, purposed veryly to be Cristen. But whan thei wist that the pestilens was among the Cristen men, than her good purpos sesed.In the XXIII. yere was the Grete Pestilens of puple. First it began in the north cuntre; than in the south; and so forth thorw oute the reme. Aftir this pestilens folowed a moreyn of bestis, whech had nevir be seyn. For, as it was supposed, there left not in Inglond the ten part of the puple. Than cesed lordes rentis, prestis tithes. Because there were so fewe tylmen, the erde lay untillid. So mech misery was in the lond, that the prosperite whech was before was nevir recured.
 * John Capgrave, The Chronicle of England