A half normal or mildly reduced white blood cell count, a relative or absolute increase in lymphocytes with a classification of up to 60% or more, a rapid increase in hematocrit in all phases, and a persistent fever with a body temperature above 39 degrees Celsius is considered flaccid fever (septic fever). In clinical medicine, the following methods are commonly used for diagnostic differentiation. 1. retention fever: the body temperature is maintained at a high level above 39-40 degrees C for several days or weeks at a constant rate. the range of temperature fluctuation within 24 hours does not exceed 1 degree C. Commonly seen in pneumococcal pneumonia, typhus and typhoid fever hyperthermia. 2.Intermittent fever: After the clinical appearance of fever or chills, the body temperature rises abruptly, up to 39℃ or more, and then drops to normal or below normal after a few hours of interval, and so repeatedly for a few hours to a few days, called periodic fever. It is seen in malaria, such as Plasmodium inter vivax or Plasmodium trisomy 21, etc. 3.Irregular fever: The range of temperature fluctuation is extremely irregular and the duration is not certain, and the temperature curve is not regular. The body temperature is often around 38℃ or fluctuates between 37 and 40℃. Clinically seen in a variety of diseases, such as upper whistle infection, mycoplasma pneumonia, tuberculosis, pleurisy, infective endocarditis, rheumatic fever, leukemia, etc., can also be seen in the interference of drugs or physical cooling. 4, wave fever: body temperature gradually increases, and then gradually decreases to low fever or normal temperature after a few days, and then gradually increases after a few days, so repeatedly, the temperature curve is wave-shaped, seen in brucellosis.