Symptoms of severe infections begin with symptoms of the infection, for example, some patients begin with fever, elevated body temperature beyond the normal range, axillary temperature over 38.3 ℃ or more, it is called fever, oral temperature over 37.8 ℃, or rectal temperature over 38.2 ℃, are called fever. Fever is one of the most common symptoms of severe infections; the other is the performance of the function of each organ, such as pneumonia, severe infections in the lungs, there will be corresponding changes in the respiratory system, such as coughing, coughing up sputum, and then there is dyspnea, respiratory increase in the performance of these; severe infections of the urinary system, there will be frequent urination, urinary urgency, and even low blood pressure; such as the liver, or reproductive infections, central nervous system infections, there are corresponding manifestations. Infections of the liver or reproductive system, central nervous system, all have corresponding manifestations. The thermoregulatory center of healthy people generally maintains the body temperature of the organs at about 37℃-38℃. If it is too high, there is a blockage of blood return, and the blockage of peripheral return reduces heat damage and leads to an increase in body temperature. This is the most common symptom inside the infection.