Patients with flaccid fever often present with a body temperature often above 39°C and fluctuates widely, with a 24-hour fluctuation range of more than 2°C, but all above normal body temperature. It is commonly seen in sepsis, rheumatic fever, severe tuberculosis and septic inflammation. In contrast, the temperature of retention fever remains constant at a high level above 39-40°C for several days or weeks, and does not fluctuate more than 1°C within 24 hours. Commonly seen in pneumococcal pneumonia, typhus and typhoid fever hyperthermia. I. Sources of infection: The main sources of infection associated with humans are sheep, cattle and pigs, followed by dogs. Patients can also be excreted from the feces, urine, milk to the outside of the bacteria, but human-to-human transmission is rarely seen. Second, the transmission route: 1, through the skin mucous membrane contact infection; 2, through the digestive tract infection; 3, through the respiratory tract infection. Susceptible people: Humans are generally susceptible, and can obtain certain immunity after the disease, and there is cross-immunity between different species of Brucella, and 2-7% of the re-infected hair, and residents of infected areas can be immune due to recessive disease.