The plague is caused by the bacterium Yersinia Pestis. Yersinia Pestis is easily destroyed by sunlight and drying but it can still live up to an hour in the air. There are 3 kinds of plague:
Enlarged lymph nodes (buboes) of bubonic plague.
Yersinia pestis bacteria, the cause of bubonic plague.
Bubonic plague is the most common type. It is caught when an infected flea bites a person. The vicitim then develops swollen and tender lymph glands, fever, headache, chills, and weakness. The disease does not spread between people.
Necrosis of finger tips of septicemic plague.
Septicemic plague occurs when plague bateria multiply in the blood. It can occur on its own or may be a combination of pneumonic and bubonic plague. Symptoms include fever, chill, abdominal pain, shock, bleeding into the skin and organs. It is not spread between people.
Lung in primary pneumonic plague. There are necrotic nodules with intense hyperemia and hemorrhage in the lower lobe, while the upper lobe contains only necrotic nodules.
Pneumonic plague is caused by inhaling the bacteria associated with the "Black Death." It begins as a severe pneumonia with high fever, chills, and cough. Without prescription antibiotics, respiratory failure and death may occur within 12 to 24 hours after the initial symptoms appear. It spreads directly from person to person through the air (e.g., cough, sneeze). A vaccine exists for prevention of bubonic plague (when the lymph nodes are infected instead of the lungs) but is not considered effective against the inhaled (pneumonic) form of this disease. Direct or close contact with an ill animal or human is required to transmit the disease.
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