The fourth level of warning for plague is a general infectious disease event, which is generally graded according to factors such as the extent of the spread and the degree of impact of the epidemic, and can be defined as a fourth level of warning when the animal plague epidemic reaches the following intensities. 1. Animal plague pandemic occurs in a certain type of plague source. 2. Animal plague epidemic occurs in a localized area, spreading to cities above the county level. 3. animal plague occurs in areas that are easily accessible and densely populated, posing a serious threat to the population. Bubonic plague is Yersinia pestis with rat fleas as the main means of transmission of virulent infectious diseases, for the international quarantine infectious diseases and China’s statutory Class A management of infectious diseases, the patient’s main clinical manifestations of high fever, lymphatic swelling and pain, hemorrhagic tendency, lung inflammation, etc., and this type of disease is not timely acceptance of the relevant treatments, the death rate of as high as 30% ~ 60%. It is recommended that if you feel sick, consult a doctor in time and do not be negligent so as not to delay your condition.