The precursors of plague are abnormally high body temperature, swollen lymph nodes with pain, hemorrhage of skin and mucous membranes, and special type of pneumonia. 1. Abnormally elevated body temperature: Yersinia pestis in plague can enter the blood circulation of the whole body and proliferate to produce various inflammatory substances leading to tissue necrosis, causing sepsis. Patients mainly manifested as abnormal elevation of body temperature, chills, followed by coma or shock. 2. Lymph node enlargement with pain: Because plague enters the human body, the first invasion is the lymph nodes. Therefore, the lymph nodes will be abnormally enlarged, and accompanied by varying degrees of pain. 3. Skin and mucous membrane hemorrhage: Because Yersinia pestis can enter the blood circulation of the whole body, leading to the destruction of blood cells and coagulation disorders, which can be manifested as skin and mucous membrane hemorrhage. 4. Special type of pneumonia:After Yersinia pestis enters the human body, it proliferates in the lung tissues and forms foci, leading to the damage of the patient’s lung tissues. Symptoms such as coughing, coughing up sputum and chest pain appear. Therefore, if you suspect that you have been infected with the plague bacteria, it is best to consult a doctor in time, complete the relevant examinations and treat the disease as soon as possible.