The document discusses the three forms of plague - bubonic, pneumonic, and septicemic - that originated from the Oriental rat flea. Bubonic plague has a mortality rate between 30-70% and symptoms include fever, headaches, and enlarged lymph nodes. Pneumonic plague infects the lungs, has symptoms that appear within 1-7 days, and a 90-100% mortality rate. Septicemic plague has a nearly 100% mortality rate and symptoms are high fever and skin turning deep purple.